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Inside Aztec
Inside
Aztec
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Building a fully decentralized, privacy-preserving network to unlock the next Renaissance.
Privacy has emerged as a major driver for the crypto industry in 2025. We’ve seen the explosion of Zcash, the Ethereum Foundation’s refocusing of PSE, and the launch of Aztec’s testnet with over 24,000 validators powering the network. Many apps have also emerged to bring private transactions to Ethereum and Solana in various ways, and exciting technologies like ZKPassport that privately bring identity on-chain using Noir have become some of the most talked about developments for ushering in the next big movements to the space.
Underpinning all of these developments is the emerging consensus that without privacy, blockchains will struggle to gain real-world adoption.
Without privacy, institutions can’t bring assets on-chain in a compliant way or conduct complex swaps and trades without revealing their strategies. Without privacy, DeFi remains dominated and controlled by advanced traders who can see all upcoming transactions and manipulate the market. Without privacy, regular people will not want to move their lives on-chain for the entire world to see every detail about their every move.
While there's been lots of talk about privacy, few can define it. In this piece we’ll outline the three pillars of privacy and gives you a framework for evaluating the privacy claims of any project.
True privacy rests on three essential pillars: transaction privacy, identity privacy, and computational privacy. It is only when we have all three pillars that we see the emergence of a private world computer.
Transaction privacy means that both inputs and outputs are not viewable by anyone other than the intended participants. Inputs include any asset, value, message, or function calldata that is being sent. Outputs include any state changes or transaction effects, or any transaction metadata caused by the transaction. Transaction privacy is often primarily achieved using a UTXO model (like Zcash or Aztec’s private state tree). If a project has only the option for this pillar, it can be said to be confidential, but not private.
Identity privacy means that the identities of those involved are not viewable by anyone other than the intended participants. This includes addresses or accounts and any information about the identity of the participants, such as tx.origin, msg.sender, or linking one’s private account to public accounts. Identity privacy can be achieved in several ways, including client-side proof generation that keeps all user info on the users’ devices. If a project has only the option for this pillar, it can be said to be anonymous, but not private.
Computation privacy means that any activity that happens is not viewable by anyone other than the intended participants. This includes the contract code itself, function execution, contract address, and full callstack privacy. Additionally, any metadata generated by the transaction is able to be appropriately obfuscated (such as transaction effects, events are appropriately padded, inclusion block number are in appropriate sets). Callstack privacy includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, any subsequent functions that will be called after, and what the inputs to the function were. A project must have the option for this pillar to do anything privately other than basic transactions.
Bitcoin ushered in a new paradigm of digital money. As a permissionless, peer-to-peer currency and store of value, it changed the way value could be sent around the world and who could participate. Ethereum expanded this vision to bring us the world computer, a decentralized, general-purpose blockchain with programmable smart contracts.
Given the limitations of running a transparent blockchain that exposes all user activity, accounts, and assets, it was clear that adding the option to preserve privacy would unlock many benefits (and more closely resemble real cash). But this was a very challenging problem. Zcash was one of the first to extend Bitcoin’s functionality with optional privacy, unlocking a new privacy-preserving UTXO model for transacting privately. As we’ll see below, many of the current privacy-focused projects are working on similar kinds of private digital money for Ethereum or other chains.
Now, Aztec is bringing us the final missing piece: a private world computer.
A private world computer is fully decentralized, programmable, and permissionless like Ethereum and has optional privacy at every level. In other words, Aztec is extending all the functionality of Ethereum with optional transaction, identity, and computational privacy. This is the only approach that enables fully compliant, decentralized applications to be built that preserve user privacy, a new design space that we see as ushering in the next Renaissance for the space.
Private digital money emerges when you have the first two privacy pillars covered - transactions and identity - but you don’t have the third - computation. Almost all projects today that claim some level of privacy are working on private digital money. This includes everything from privacy pools on Ethereum and L2s to newly emerging payment L1s like Tempo and Arc that are developing various degrees of transaction privacy
When it comes to digital money, privacy exists on a spectrum. If your identity is hidden but your transactions are visible, that's what we call anonymous. If your transactions are hidden but your identity is known, that's confidential. And when both your identity and transactions are protected, that's true privacy. Projects are working on many different approaches to implement this, from PSE to Payy using Noir, the zkDSL built to make it intuitive to build zk applications using familiar Rust-like syntax.
Private digital money is designed to make payments private, but any interaction with more complex smart contracts than a straightforward payment transaction is fully exposed.
What if we also want to build decentralized private apps using smart contracts (usually multiple that talk to each other)? For this, you need all three privacy pillars: transaction, identity, and compute.
If you have these three pillars covered and you have decentralization, you have built a private world computer. Without decentralization, you are vulnerable to censorship, privileged backdoors and inevitable centralized control that can compromise privacy guarantees.
What exactly is a private world computer? A private world computer extends all the functionality of Ethereum with optional privacy at every level, so developers can easily control which aspects they want public or private and users can selectively disclose information. With Aztec, developers can build apps with optional transaction, identity, and compute privacy on a fully decentralized network. Below, we’ll break down the main components of a private world computer.
A private world computer is powered by private smart contracts. Private smart contracts have fully optional privacy and also enable seamless public and private function interaction.
Private smart contracts simply extend the functionality of regular smart contracts with added privacy.
As a developer, you can easily designate which functions you want to keep private and which you want to make public. For example, a voting app might allow users to privately cast votes and publicly display the result. Private smart contracts can also interact privately with other smart contracts, without needing to make it public which contracts have interacted.
Transaction: Aztec supports the optionality for fully private inputs, including messages, state, and function calldata. Private state is updated via a private UTXO state tree.
Identity: Using client-side proofs and function execution, Aztec can optionally keep all user info private, including tx.origin and msg.sender for transactions.
Computation: The contract code itself, function execution, and call stack can all be kept private. This includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, and what the inputs to the function were.
A decentralized network must be made up of a permissionless network of operators who run the network and decide on upgrades. Aztec is run by a decentralized network of node operators who propose and attest to transactions. Rollup proofs on Aztec are also run by a decentralized prover network that can permissionlessly submit proofs and participate in block rewards. Finally, the Aztec network is governed by the sequencers, who propose, signal, vote, and execute network upgrades.
A private world computer enables the creation of DeFi applications where accounts, transactions, order books, and swaps remain private. Users can protect their trading strategies and positions from public view, preventing front-running and maintaining competitive advantages. Additionally, users can bridge privately into cross-chain DeFi applications, allowing them to participate in DeFi across multiple blockchains while keeping their identity private despite being on an existing transparent blockchain.
This technology makes it possible to bring institutional trading activity on-chain while maintaining the privacy that traditional finance requires. Institutions can privately trade with other institutions globally, without having to touch public markets, enjoying the benefits of blockchain technology such as fast settlement and reduced counterparty risk, without exposing their trading intentions or volumes to the broader market.
Organizations can bring client accounts and assets on-chain while maintaining full compliance. This infrastructure protects on-chain asset trading and settlement strategies, ensuring that sophisticated financial operations remain private. A private world computer also supports private stablecoin issuance and redemption, allowing financial institutions to manage digital currency operations without revealing sensitive business information.
Users have granular control over their privacy settings, allowing them to fine-tune privacy levels for their on-chain identity according to their specific needs. The system enables selective disclosure of on-chain activity, meaning users can choose to reveal certain transactions or holdings to regulators, auditors, or business partners while keeping other information private, meeting compliance requirements.
The shift from transparent blockchains to privacy-preserving infrastructure is the foundation for bringing the next billion users on-chain. Whether you're a developer building the future of private DeFi, an institution exploring compliant on-chain solutions, or simply someone who believes privacy is a fundamental right, now is the time to get involved.
Follow Aztec on X to stay updated on the latest developments in private smart contracts and decentralized privacy technology. Ready to contribute to the network? Run a node and help power the private world computer.
The next Renaissance is here, and it’s being powered by the private world computer.
Special thanks to Santiago Palladino, Phil Windle, Alex Gherghisan, and Mitch Tracy for technical updates and review.
On September 17th, 2025, a new network upgrade was deployed, making Aztec more secure and flexible for home stakers. This upgrade, shipped with all the features needed for a fully decentralized network launch, includes a completely redesigned slashing system that allows inactive or malicious operators to be removed, and does not penalize home stakers for short outages.
With over 23,000 operators running validators across 6 continents (in a variety of conditions), it is critical not to penalize nodes that temporarily drop due to internet connectivity issues. This is because users of the network are also found across the globe, some of whom might have older phones. A significant effort was put into shipping a low-memory proving mode that allows older mobile devices to send transactions and use privacy-preserving apps.
The network was successfully deployed, and all active validators on the old testnet were added to the queue of the new testnet. This manual migration was only necessary because major upgrades to the governance contracts had gone in since the last testnet was deployed. The new testnet started producing blocks after the queue started to be “flushed,” moving validators into the rollup. Because the network is fully decentralized, the initial flush could have been called by anyone. The network produced ~2k blocks before an invalid block made it to the chain and temporarily stalled block production. Block production is now restored and the network is healthy. This post explains what caused the issue and provides an update on the current status of the network.
Note: if you are a network operator, you must upgrade to version 2.0.3 and restart your node to participate in the latest testnet. If you want to run a node, it’s easy to get started.
This upgrade was a team-wide effort that optimized performance and implemented all the mechanisms needed to launch Aztec as a fully decentralized network from day 1.
With these updates in place, we’re ready to test a feature-complete network.
As mentioned above, block production started when someone called the flush function and a minimum number of operators from the queue were let into the validator set.
Shortly thereafter, while testing the network, a member of the Aztec Labs team spun up a “bad” sequencer that produced an invalid block proposal. Specifically, one of the state trees in the proposal was tampered with.
The expectation was that this would be detected immediately and the block rejected. Instead, a bug was discovered in the validator code where the invalid block proposal wasn't checked thoroughly enough. In effect, the proposal got enough attestations, so it was posted to the rollup. Due to extra checks in the nodes, when the nodes pulled the invalid block from Ethereum, they detected the tampered tree and refused to sync it. This is a good outcome as it prevented the attack. Additionally, prover nodes refused to prove the epoch containing the invalid block. This allowed the rollup to prune the entire bad epoch away. After the prune, the invalid state was reset to the last known good block.
The prune revealed another, smaller bug, where, after a failed block sync, a prune does not get processed correctly, requiring a node restart to clear up. This led to a 90-minute outage from the moment the block proposal was posted until the testnet recovered. The time was equally split between waiting for pruning to happen and for the nodes to restart in order to process the prune.
Validators were correctly re-executing all transactions in the block proposals and verifying that the world state root matched the one in the block proposal, but they failed to check that intermediate tree roots, which are included in the proposal and posted to the rollup contract on L1, were also correct. The attack tweaked one of these intermediate roots while proposing a correct world state root, so it went unnoticed by the attestors.
As mentioned above, even though the block made it through the initial attestation and was posted to L1, the invalid block was caught by the validators, and the entire epoch was never proven as provers refused to generate a proof for the inconsistent state.
A fix was pushed that resolved this issue and ensured that invalid block proposals would be caught and rejected. A second fix was pushed that ensures inconsistent state is removed from the uncommitted cache of the world state.
Block production is currently running smoothly, and the network health has been restored.
Operators who had previously upgraded to version 2.0.3 will need to restart their nodes. Any operator who has not upgraded to 2.0.3 should do so immediately.
Slashing has also been functioning as expected. Below you can see the slashing signals for each round. A single signal can contain votes for multiple validators, but a validator's attester needs to receive 65 votes to be slashed.
Join us this Thursday, September 25, 2025, at 4 PM CET on the Discord Town Hall to hear more about the 2.0.3 upgrade. To stay up to date with the latest updates for network operators, join the Aztec Discord and follow Aztec on X.
Payy, a privacy-focused payment network, just rewrote its entire ZK architecture from Halo2 to Noir while keeping its network live, funds safe, and users happy.
Code that took months to write now takes weeks (with MVPs built in as little as 30 minutes). Payy’s codebase shrank from thousands of lines to 250, and now their entire engineering team can actually work on its privacy infra.
This is the story of how they transformed their ZK ecosystem from one bottlenecked by a single developer to a system their entire team can modify and maintain.
Eighteen months ago, Payy faced a deceptively simple requirement: build a privacy-preserving payment network that actually works on phones. That requires client-side proving.
"Anyone who tells you they can give you privacy without the proof being on the phone is lying to you," Calum Moore - Payy's Technical Lead - states bluntly.
To make a private, mobile network work, they needed:
To start, the team evaluated available ZK stacks through their zkbench framework:
STARKs (e.g., RISC Zero): Memory requirements made them a non-starter on mobile. Large proof sizes are unsuitable for mobile data transmission.
Circom with Groth16: Required trusted setup ceremonies for each circuit update. It had “abstracted a bit too early” and, as a result, is not high-level enough to develop comfortably, but not low-level enough for controls and optimizations, said Calum.
Halo2: Selected based on existing production deployments (ZCash, Scroll), small proof sizes, and an existing Ethereum verifier. As Calum admitted with the wisdom of hindsight: “Back a year and a half ago, there weren’t any other real options.”
Halo2 delivered on its promises: Payy successfully launched its network. But cracks started showing almost immediately.
First, they had to write their own chips from scratch. Then came the real fun: if statements.
"With Halo2, I'm building a chip, I'm passing this chip in... It's basically a container chip, so you'd set the value to zero or one depending on which way you want it to go. And, you'd zero out the previous value if you didn't want it to make a difference to the calculation," Calum explained, “when I’m writing in Noir, I just write ‘if’. "
With Halo2, writing an if statement (programming 101) required building custom chip infra.
Binary decomposition, another fundamental operation for rollups, meant more custom chips. The Halo2 implementation quickly grew to thousands of lines of incomprehensible code.
And only Calum could touch any of it.
The Bottleneck
"It became this black box that no one could touch, no one could reason about, no one could verify," he recalls. "Obviously, we had it audited, and we were confident in that. But any changes could only be done by me, could only be verified by me or an auditor."
In engineering terms, this is called a bus factor of one: if Calum got hit by a bus (or took a vacation to Argentina), Payy's entire proving system would be frozen. "Those circuits are open source," Calum notes wryly, "but who's gonna be able to read the Halo2 circuits? Nobody."
During a launch event in Argentina, "I was like, oh, I'll check out Noir again. See how it's going," Calum remembers. He'd been tracking Noir's progress for months, occasionally testing it out, waiting for it to be reliable.
"I wrote basically our entire client-side proof in about half an hour in Noir. And it probably took me - I don't know, three weeks to write that proof originally in Halo2."
Calum recreated Payy's client-side proof in Noir in 30 minutes. And when he tested the proving speed, without any optimization, they were seeing 2x speed improvements.
"I kind of internally… didn't want to tell my cofounder Sid that I'd already made my decision to move to Noir," Calum admits. "I hadn't broken it to him yet because it's hard to justify rewriting your proof system when you have a deployed network with a bunch of money already on the network and a bunch of users."
Convincing a team to rewrite the core of a live financial network takes some evidence. The technical evaluation of Noir revealed improvements across every metric:
Proof Generation Time: Sub-0.5 second proof generation on iPhones. "We're obsessive about performance," Calum notes (they’re confident they can push it even further).
Code Complexity: Their entire ZK implementation compressed from thousands of lines of Halo2 to just 250 lines of Noir code. "With rollups, the logic isn't complex—it's more about the preciseness of the logic," Calum explains.
Composability: In Halo2, proof aggregation required hardwiring specific verifiers for each proof type. Noir offers a general-purpose verifier that accepts any proof of consistent size.
"We can have 100 different proving systems, which are hyper-efficient for the kind of application that we're doing," Calum explains. "Have them all aggregated by the same aggregation proof, and reason about whatever needs to be."
Initially, the goal was to "completely mirror our Halo2 proofs": no new features. This conservative approach meant they could verify correctness while maintaining a live network.
The migration preserved Payy's production architecture:
"If you have your proofs in Noir, any person who understands even a little bit about logic or computers can go in and say, 'okay, I can kinda see what's happening here'," Calum notes.
The audit process completely transformed. With Halo2: "The auditors that are available to audit Halo2 are few and far between."
With Noir: "You could have an auditor that had no Noir experience do at least a 95% job."
Why? Most audit issues are logic errors, not ZK-specific bugs. When auditors can read your code, they find real problems instead of getting lost in implementation details.
Halo2: Binary decomposition
Payy’s previous 383 line implementation of binary decomposition can be viewed here (pkg/zk-circuits/src/chips/binary_decomposition.rs).
Payy’s previous binary decomposition implementation
Meanwhile, binary decomposition is handled in Noir with the following single line.
pub fn to_le_bits<let N: u32>(self: Self) -> [u1; N]
(Source)
With Noir's composable proof system, Payy can now build specialized provers for different operations, each optimized for its specific task.
"If statements are horrendous in SNARKs because you pay the cost of the if statement regardless of its run," Calum explains. But with Noir's approach, "you can split your application logic into separate proofs, and run whichever proof is for the specific application you're looking for."
Instead of one monolithic proof trying to handle every case, you can have specialized proofs, each perfect for its purpose.
"I fell a little bit in love with Halo2," Calum admits, "maybe it's Stockholm syndrome where you're like, you know, it's a love-hate relationship, and it's really hard. But at the same time, when you get a breakthrough with it, you're like, yes, I feel really good because I'm basically writing assembly-level ZK proofs."
“But now? I just write ‘if’.”
Technical Note: While "migrating from Halo2 to Noir" is shorthand that works for this article, technically Halo2 is an integrated proving system where circuits must be written directly in Rust using its constraint APIs, while Noir is a high-level language that compiles to an intermediate representation and can use various proving backends. Payy specifically moved from writing circuits in Halo2's low-level constraint system to writing them in Noir's high-level language, with Barretenberg (UltraHonk) as their proving backend.
Both tools ultimately enable developers to write circuits and generate proofs, but Noir's modular architecture separates circuit logic from the proving system - which is what made Payy's circuits so much more accessible to their entire team, and now allows them to swap out their proving system with minimal effort as proving systems improve.
Payy's code is open source and available for developers looking to learn from their implementation.
After eight years of solving impossible problems, the next renaissance is here.
We’re at a major inflection point, with both our tech and our builder community going through growth spurts. The purpose of this rebrand is simple: to draw attention to our full-stack privacy-native network and to elevate the rich community of builders who are creating a thriving ecosystem around it.
For eight years, we’ve been obsessed with solving impossible challenges. We invented new cryptography (Plonk), created an intuitive programming language (Noir), and built the first decentralized network on Ethereum where privacy is native rather than an afterthought.
It wasn't easy. But now, we're finally bringing that powerful network to life. Testnet is live with thousands of active users and projects that were technically impossible before Aztec.
Our community evolution mirrors our technical progress. What started as an intentionally small, highly engaged group of cracked developers is now welcoming waves of developers eager to build applications that mainstream users actually want and need.
A brand is more than aesthetics—it's a mental model that makes Aztec's spirit tangible.
Renaissance means "rebirth"—and that's exactly what happens when developers gain access to privacy-first infrastructure. We're witnessing the emergence of entirely new application categories, business models, and user experiences.
The faces of this renaissance are the builders we serve: the entrepreneurs building privacy-preserving DeFi, the activists building identity systems that protect user privacy, the enterprise architects tokenizing real-world assets, and the game developers creating experiences with hidden information.
This next renaissance isn't just about technology—it's about the ethos behind the build. These aren't just our values. They're the shared DNA of every builder pushing the boundaries of what's possible on Aztec.
Agency: It’s what everyone deserves, and very few truly have: the ability to choose and take action for ourselves. On the Aztec Network, agency is native
Genius: That rare cocktail of existential thirst, extraordinary brilliance, and mind-bending creation. It’s fire that fuels our great leaps forward.
Integrity: It’s the respect and compassion we show each other. Our commitment to attacking the hardest problems first, and the excellence we demand of any solution.
Obsession: That highly concentrated insanity, extreme doggedness, and insatiable devotion that makes us tick. We believe in a different future—and we can make it happen, together.
Just as our technology bridges different eras of cryptographic innovation, our new visual identity draws from multiple periods of human creativity and technological advancement.
Our new wordmark embodies the diversity of our community and the permissionless nature of our network. Each letter was custom-drawn to reflect different pivotal moments in human communication and technological progress.
Together, these letters tell the story of human innovation: each era building on the last, each breakthrough enabling the next renaissance. And now, we're building the infrastructure for the one that's coming.
We evolved our original icon to reflect this new chapter while honoring our foundation. The layered diamond structure tells the story:
The architecture echoes a central plaza—the Roman forum, the Greek agora, the English commons, the American town square—places where people gather, exchange ideas, build relationships, and shape culture. It's a fitting symbol for the infrastructure enabling the next leap in human coordination and creativity.
From the Mughal and Edo periods to the Flemish and Italian Renaissance, our brand imagery draws from different cultures and eras of extraordinary human flourishing—periods when science, commerce, culture and technology converged to create unprecedented leaps forward. These visuals reflect both the universal nature of the Renaissance and the global reach of our network.
But we're not just celebrating the past —we're creating the future: the infrastructure for humanity's next great creative and technological awakening, powered by privacy-native blockchain technology.
Join us to ask questions, learn more and dive into the lore.
Join Our Discord Town Hall. September 4th at 8 AM PT, then every Thursday at 7 AM PT. Come hear directly from our team, ask questions, and connect with other builders who are shaping the future of privacy-first applications.
Take your stance on privacy. Visit the privacy glyph generator to create your custom profile pic and build this new world with us.
Stay Connected. Visit the new website and to stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
The next renaissance is what you build on Aztec—and we can't wait to see what you'll create.
Aztec’s Public Testnet launched in May 2025.
Since then, we’ve been obsessively working toward our ultimate goal: launching the first fully decentralized privacy-preserving layer-2 (L2) network on Ethereum. This effort has involved a team of over 70 people, including world-renowned cryptographers and builders, with extensive collaboration from the Aztec community.
To make something private is one thing, but to also make it decentralized is another. Privacy is only half of the story. Every component of the Aztec Network will be decentralized from day one because decentralization is the foundation that allows privacy to be enforced by code, not by trust. This includes sequencers, which order and validate transactions, provers, which create privacy-preserving cryptographic proofs, and settlement on Ethereum, which finalizes transactions on the secure Ethereum mainnet to ensure trust and immutability.
Strong progress is being made by the community toward full decentralization. The Aztec Network now includes nearly 1,000 sequencers in its validator set, with 15,000 nodes spread across more than 50 countries on six continents. With this globally distributed network in place, the Aztec Network is ready for users to stress test and challenge its resilience.
We're now entering a new phase: the Adversarial Testnet. This stage will test the resilience of the Aztec Testnet and its decentralization mechanisms.
The Adversarial Testnet introduces two key features: slashing, which penalizes validators for malicious or negligent behavior in Proof-of-Stake (PoS) networks, and a fully decentralized governance mechanism for protocol upgrades.
This phase will also simulate network attacks to test its ability to recover independently, ensuring it could continue to operate even if the core team and servers disappeared (see more on Vitalik’s “walkaway test” here). It also opens the validator set to more people using ZKPassport, a private identity verification app, to verify their identity online.
The Aztec Network testnet is decentralized, run by a permissionless network of sequencers.
The slashing upgrade tests one of the most fundamental mechanisms for removing inactive or malicious sequencers from the validator set, an essential step toward strengthening decentralization.
Similar to Ethereum, on the Aztec Network, any inactive or malicious sequencers will be slashed and removed from the validator set. Sequencers will be able to slash any validator that makes no attestations for an entire epoch or proposes an invalid block.
Three slashes will result in being removed from the validator set. Sequencers may rejoin the validator set at any time after getting slashed; they just need to rejoin the queue.
In addition to testing network resilience when validators go offline and evaluating the slashing mechanisms, the Adversarial Testnet will also assess the robustness of the network’s decentralized governance during protocol upgrades.
Adversarial Testnet introduces changes to Aztec Network’s governance system.
Sequencers now have an even more central role, as they are the sole actors permitted to deposit assets into the Governance contract.
After the upgrade is defined and the proposed contracts are deployed, sequencers will vote on and implement the upgrade independently, without any involvement from Aztec Labs and/or the Aztec Foundation.
Starting today, you can join the Adversarial Testnet to help battle-test Aztec’s decentralization and security. Anyone can compete in six categories for a chance to win exclusive Aztec swag, be featured on the Aztec X account, and earn a DappNode. The six challenge categories include:
Performance will be tracked using Dashtec, a community-built dashboard that pulls data from publicly available sources. Dashtec displays a weighted score of your validator performance, which may be used to evaluate challenges and award prizes.
The dashboard offers detailed insights into sequencer performance through a stunning UI, allowing users to see exactly who is in the current validator set and providing a block-by-block view of every action taken by sequencers.
To join the validator set and start tracking your performance, click here. Join us on Thursday, July 31, 2025, at 4 pm CET on Discord for a Town Hall to hear more about the challenges and prizes. Who knows, we might even drop some alpha.
To stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
Privacy has emerged as a major driver for the crypto industry in 2025. We’ve seen the explosion of Zcash, the Ethereum Foundation’s refocusing of PSE, and the launch of Aztec’s testnet with over 24,000 validators powering the network. Many apps have also emerged to bring private transactions to Ethereum and Solana in various ways, and exciting technologies like ZKPassport that privately bring identity on-chain using Noir have become some of the most talked about developments for ushering in the next big movements to the space.
Underpinning all of these developments is the emerging consensus that without privacy, blockchains will struggle to gain real-world adoption.
Without privacy, institutions can’t bring assets on-chain in a compliant way or conduct complex swaps and trades without revealing their strategies. Without privacy, DeFi remains dominated and controlled by advanced traders who can see all upcoming transactions and manipulate the market. Without privacy, regular people will not want to move their lives on-chain for the entire world to see every detail about their every move.
While there's been lots of talk about privacy, few can define it. In this piece we’ll outline the three pillars of privacy and gives you a framework for evaluating the privacy claims of any project.
True privacy rests on three essential pillars: transaction privacy, identity privacy, and computational privacy. It is only when we have all three pillars that we see the emergence of a private world computer.
Transaction privacy means that both inputs and outputs are not viewable by anyone other than the intended participants. Inputs include any asset, value, message, or function calldata that is being sent. Outputs include any state changes or transaction effects, or any transaction metadata caused by the transaction. Transaction privacy is often primarily achieved using a UTXO model (like Zcash or Aztec’s private state tree). If a project has only the option for this pillar, it can be said to be confidential, but not private.
Identity privacy means that the identities of those involved are not viewable by anyone other than the intended participants. This includes addresses or accounts and any information about the identity of the participants, such as tx.origin, msg.sender, or linking one’s private account to public accounts. Identity privacy can be achieved in several ways, including client-side proof generation that keeps all user info on the users’ devices. If a project has only the option for this pillar, it can be said to be anonymous, but not private.
Computation privacy means that any activity that happens is not viewable by anyone other than the intended participants. This includes the contract code itself, function execution, contract address, and full callstack privacy. Additionally, any metadata generated by the transaction is able to be appropriately obfuscated (such as transaction effects, events are appropriately padded, inclusion block number are in appropriate sets). Callstack privacy includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, any subsequent functions that will be called after, and what the inputs to the function were. A project must have the option for this pillar to do anything privately other than basic transactions.
Bitcoin ushered in a new paradigm of digital money. As a permissionless, peer-to-peer currency and store of value, it changed the way value could be sent around the world and who could participate. Ethereum expanded this vision to bring us the world computer, a decentralized, general-purpose blockchain with programmable smart contracts.
Given the limitations of running a transparent blockchain that exposes all user activity, accounts, and assets, it was clear that adding the option to preserve privacy would unlock many benefits (and more closely resemble real cash). But this was a very challenging problem. Zcash was one of the first to extend Bitcoin’s functionality with optional privacy, unlocking a new privacy-preserving UTXO model for transacting privately. As we’ll see below, many of the current privacy-focused projects are working on similar kinds of private digital money for Ethereum or other chains.
Now, Aztec is bringing us the final missing piece: a private world computer.
A private world computer is fully decentralized, programmable, and permissionless like Ethereum and has optional privacy at every level. In other words, Aztec is extending all the functionality of Ethereum with optional transaction, identity, and computational privacy. This is the only approach that enables fully compliant, decentralized applications to be built that preserve user privacy, a new design space that we see as ushering in the next Renaissance for the space.
Private digital money emerges when you have the first two privacy pillars covered - transactions and identity - but you don’t have the third - computation. Almost all projects today that claim some level of privacy are working on private digital money. This includes everything from privacy pools on Ethereum and L2s to newly emerging payment L1s like Tempo and Arc that are developing various degrees of transaction privacy
When it comes to digital money, privacy exists on a spectrum. If your identity is hidden but your transactions are visible, that's what we call anonymous. If your transactions are hidden but your identity is known, that's confidential. And when both your identity and transactions are protected, that's true privacy. Projects are working on many different approaches to implement this, from PSE to Payy using Noir, the zkDSL built to make it intuitive to build zk applications using familiar Rust-like syntax.
Private digital money is designed to make payments private, but any interaction with more complex smart contracts than a straightforward payment transaction is fully exposed.
What if we also want to build decentralized private apps using smart contracts (usually multiple that talk to each other)? For this, you need all three privacy pillars: transaction, identity, and compute.
If you have these three pillars covered and you have decentralization, you have built a private world computer. Without decentralization, you are vulnerable to censorship, privileged backdoors and inevitable centralized control that can compromise privacy guarantees.
What exactly is a private world computer? A private world computer extends all the functionality of Ethereum with optional privacy at every level, so developers can easily control which aspects they want public or private and users can selectively disclose information. With Aztec, developers can build apps with optional transaction, identity, and compute privacy on a fully decentralized network. Below, we’ll break down the main components of a private world computer.
A private world computer is powered by private smart contracts. Private smart contracts have fully optional privacy and also enable seamless public and private function interaction.
Private smart contracts simply extend the functionality of regular smart contracts with added privacy.
As a developer, you can easily designate which functions you want to keep private and which you want to make public. For example, a voting app might allow users to privately cast votes and publicly display the result. Private smart contracts can also interact privately with other smart contracts, without needing to make it public which contracts have interacted.
Transaction: Aztec supports the optionality for fully private inputs, including messages, state, and function calldata. Private state is updated via a private UTXO state tree.
Identity: Using client-side proofs and function execution, Aztec can optionally keep all user info private, including tx.origin and msg.sender for transactions.
Computation: The contract code itself, function execution, and call stack can all be kept private. This includes which contracts you call, what functions in those contracts you’ve called, what the results of those functions were, and what the inputs to the function were.
A decentralized network must be made up of a permissionless network of operators who run the network and decide on upgrades. Aztec is run by a decentralized network of node operators who propose and attest to transactions. Rollup proofs on Aztec are also run by a decentralized prover network that can permissionlessly submit proofs and participate in block rewards. Finally, the Aztec network is governed by the sequencers, who propose, signal, vote, and execute network upgrades.
A private world computer enables the creation of DeFi applications where accounts, transactions, order books, and swaps remain private. Users can protect their trading strategies and positions from public view, preventing front-running and maintaining competitive advantages. Additionally, users can bridge privately into cross-chain DeFi applications, allowing them to participate in DeFi across multiple blockchains while keeping their identity private despite being on an existing transparent blockchain.
This technology makes it possible to bring institutional trading activity on-chain while maintaining the privacy that traditional finance requires. Institutions can privately trade with other institutions globally, without having to touch public markets, enjoying the benefits of blockchain technology such as fast settlement and reduced counterparty risk, without exposing their trading intentions or volumes to the broader market.
Organizations can bring client accounts and assets on-chain while maintaining full compliance. This infrastructure protects on-chain asset trading and settlement strategies, ensuring that sophisticated financial operations remain private. A private world computer also supports private stablecoin issuance and redemption, allowing financial institutions to manage digital currency operations without revealing sensitive business information.
Users have granular control over their privacy settings, allowing them to fine-tune privacy levels for their on-chain identity according to their specific needs. The system enables selective disclosure of on-chain activity, meaning users can choose to reveal certain transactions or holdings to regulators, auditors, or business partners while keeping other information private, meeting compliance requirements.
The shift from transparent blockchains to privacy-preserving infrastructure is the foundation for bringing the next billion users on-chain. Whether you're a developer building the future of private DeFi, an institution exploring compliant on-chain solutions, or simply someone who believes privacy is a fundamental right, now is the time to get involved.
Follow Aztec on X to stay updated on the latest developments in private smart contracts and decentralized privacy technology. Ready to contribute to the network? Run a node and help power the private world computer.
The next Renaissance is here, and it’s being powered by the private world computer.
After eight years of solving impossible problems, the next renaissance is here.
We’re at a major inflection point, with both our tech and our builder community going through growth spurts. The purpose of this rebrand is simple: to draw attention to our full-stack privacy-native network and to elevate the rich community of builders who are creating a thriving ecosystem around it.
For eight years, we’ve been obsessed with solving impossible challenges. We invented new cryptography (Plonk), created an intuitive programming language (Noir), and built the first decentralized network on Ethereum where privacy is native rather than an afterthought.
It wasn't easy. But now, we're finally bringing that powerful network to life. Testnet is live with thousands of active users and projects that were technically impossible before Aztec.
Our community evolution mirrors our technical progress. What started as an intentionally small, highly engaged group of cracked developers is now welcoming waves of developers eager to build applications that mainstream users actually want and need.
A brand is more than aesthetics—it's a mental model that makes Aztec's spirit tangible.
Renaissance means "rebirth"—and that's exactly what happens when developers gain access to privacy-first infrastructure. We're witnessing the emergence of entirely new application categories, business models, and user experiences.
The faces of this renaissance are the builders we serve: the entrepreneurs building privacy-preserving DeFi, the activists building identity systems that protect user privacy, the enterprise architects tokenizing real-world assets, and the game developers creating experiences with hidden information.
This next renaissance isn't just about technology—it's about the ethos behind the build. These aren't just our values. They're the shared DNA of every builder pushing the boundaries of what's possible on Aztec.
Agency: It’s what everyone deserves, and very few truly have: the ability to choose and take action for ourselves. On the Aztec Network, agency is native
Genius: That rare cocktail of existential thirst, extraordinary brilliance, and mind-bending creation. It’s fire that fuels our great leaps forward.
Integrity: It’s the respect and compassion we show each other. Our commitment to attacking the hardest problems first, and the excellence we demand of any solution.
Obsession: That highly concentrated insanity, extreme doggedness, and insatiable devotion that makes us tick. We believe in a different future—and we can make it happen, together.
Just as our technology bridges different eras of cryptographic innovation, our new visual identity draws from multiple periods of human creativity and technological advancement.
Our new wordmark embodies the diversity of our community and the permissionless nature of our network. Each letter was custom-drawn to reflect different pivotal moments in human communication and technological progress.
Together, these letters tell the story of human innovation: each era building on the last, each breakthrough enabling the next renaissance. And now, we're building the infrastructure for the one that's coming.
We evolved our original icon to reflect this new chapter while honoring our foundation. The layered diamond structure tells the story:
The architecture echoes a central plaza—the Roman forum, the Greek agora, the English commons, the American town square—places where people gather, exchange ideas, build relationships, and shape culture. It's a fitting symbol for the infrastructure enabling the next leap in human coordination and creativity.
From the Mughal and Edo periods to the Flemish and Italian Renaissance, our brand imagery draws from different cultures and eras of extraordinary human flourishing—periods when science, commerce, culture and technology converged to create unprecedented leaps forward. These visuals reflect both the universal nature of the Renaissance and the global reach of our network.
But we're not just celebrating the past —we're creating the future: the infrastructure for humanity's next great creative and technological awakening, powered by privacy-native blockchain technology.
Join us to ask questions, learn more and dive into the lore.
Join Our Discord Town Hall. September 4th at 8 AM PT, then every Thursday at 7 AM PT. Come hear directly from our team, ask questions, and connect with other builders who are shaping the future of privacy-first applications.
Take your stance on privacy. Visit the privacy glyph generator to create your custom profile pic and build this new world with us.
Stay Connected. Visit the new website and to stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
The next renaissance is what you build on Aztec—and we can't wait to see what you'll create.
Aztec’s Public Testnet launched in May 2025.
Since then, we’ve been obsessively working toward our ultimate goal: launching the first fully decentralized privacy-preserving layer-2 (L2) network on Ethereum. This effort has involved a team of over 70 people, including world-renowned cryptographers and builders, with extensive collaboration from the Aztec community.
To make something private is one thing, but to also make it decentralized is another. Privacy is only half of the story. Every component of the Aztec Network will be decentralized from day one because decentralization is the foundation that allows privacy to be enforced by code, not by trust. This includes sequencers, which order and validate transactions, provers, which create privacy-preserving cryptographic proofs, and settlement on Ethereum, which finalizes transactions on the secure Ethereum mainnet to ensure trust and immutability.
Strong progress is being made by the community toward full decentralization. The Aztec Network now includes nearly 1,000 sequencers in its validator set, with 15,000 nodes spread across more than 50 countries on six continents. With this globally distributed network in place, the Aztec Network is ready for users to stress test and challenge its resilience.
We're now entering a new phase: the Adversarial Testnet. This stage will test the resilience of the Aztec Testnet and its decentralization mechanisms.
The Adversarial Testnet introduces two key features: slashing, which penalizes validators for malicious or negligent behavior in Proof-of-Stake (PoS) networks, and a fully decentralized governance mechanism for protocol upgrades.
This phase will also simulate network attacks to test its ability to recover independently, ensuring it could continue to operate even if the core team and servers disappeared (see more on Vitalik’s “walkaway test” here). It also opens the validator set to more people using ZKPassport, a private identity verification app, to verify their identity online.
The Aztec Network testnet is decentralized, run by a permissionless network of sequencers.
The slashing upgrade tests one of the most fundamental mechanisms for removing inactive or malicious sequencers from the validator set, an essential step toward strengthening decentralization.
Similar to Ethereum, on the Aztec Network, any inactive or malicious sequencers will be slashed and removed from the validator set. Sequencers will be able to slash any validator that makes no attestations for an entire epoch or proposes an invalid block.
Three slashes will result in being removed from the validator set. Sequencers may rejoin the validator set at any time after getting slashed; they just need to rejoin the queue.
In addition to testing network resilience when validators go offline and evaluating the slashing mechanisms, the Adversarial Testnet will also assess the robustness of the network’s decentralized governance during protocol upgrades.
Adversarial Testnet introduces changes to Aztec Network’s governance system.
Sequencers now have an even more central role, as they are the sole actors permitted to deposit assets into the Governance contract.
After the upgrade is defined and the proposed contracts are deployed, sequencers will vote on and implement the upgrade independently, without any involvement from Aztec Labs and/or the Aztec Foundation.
Starting today, you can join the Adversarial Testnet to help battle-test Aztec’s decentralization and security. Anyone can compete in six categories for a chance to win exclusive Aztec swag, be featured on the Aztec X account, and earn a DappNode. The six challenge categories include:
Performance will be tracked using Dashtec, a community-built dashboard that pulls data from publicly available sources. Dashtec displays a weighted score of your validator performance, which may be used to evaluate challenges and award prizes.
The dashboard offers detailed insights into sequencer performance through a stunning UI, allowing users to see exactly who is in the current validator set and providing a block-by-block view of every action taken by sequencers.
To join the validator set and start tracking your performance, click here. Join us on Thursday, July 31, 2025, at 4 pm CET on Discord for a Town Hall to hear more about the challenges and prizes. Who knows, we might even drop some alpha.
To stay up-to-date on all things Noir and Aztec, make sure you’re following along on X.
On May 1st, 2025, Aztec Public Testnet went live.
Within the first 24 hours, over 20k users visited the Aztec Playground and started to send transactions on testnet. Additionally, 10 apps launched live on the testnet, including wallets, block explorers, and private DeFi and NFT marketplaces. Launching a decentralized testnet poses significant challenges, and we’re proud that the network has continued to run despite high levels of congestion that led to slow block production for a period of time.
Around 6 hours after announcing the network launch, more than 150 sequencers had joined the validator set to sequence transactions and propose blocks for the network. 500+ additional full nodes were spun up by node operators participating in our Discord community. These sequencers were flooded with over 5k transactions before block production slowed. Let’s dive into why block production slowed down.
On Aztec, an epoch is a group of 32 blocks that are rolled up for settlement on Ethereum. Leading up to the slowdown of block production, there were entire epochs with full blocks (8 transactions, or 0.2TPS) in every slot. The sequencers were building blocks and absorbing the demand for blockspace from users of the Aztec playground, and there was a build up of 100s of pending transactions in sequencer mempools.
Issues arose when these transactions started to exceed the mempool size, which was configured to hold only 100mb or about 700 transactions.
As many new validators were brought through the funnel and started to come online, the mempools of existing validators (already full at 700 transactions) and new ones (at 0 transactions) diverged significantly. When earlier validators proposed blocks, newer validators didn't have the transactions and could not attest to blocks because the request/response protocol wasn't aggressive enough. When newer validators made proposals, earlier validators didn't have transactions (their mempools were full), so they could not attest to blocks.
New validators then started to build up pending transactions. When validators with full mempools requested missing transactions from peers, they would evict existing transactions from their mempools (mempool is at max memory) based on priority fee. All transactions had default fee settings, so validators were randomly ejecting transactions and were not doing so in lockstep (different validators ejected different transactions). For a little over an hour, the mempools diverged significantly from each other, and block production slowed down to about 20% of the expected rate.
In order to stop the mempool from ejecting transactions, the p2p mempool size was increased. By increasing the mempool size, the likelihood of needing to evict transactions that might soon appear in proposals is reduced. This increases the chances that sequencers already have the necessary transactions locally when they receive a block proposal. As a result, more validators are able to attest to proposals, allowing blocks to be finalized more reliably. Once blocks are included on L1, their transactions are evicted from the mempool. So over time, as more blocks are finalized and transactions are mined, the mempool naturally shrinks and the network will recover on its own.
If you are interested in running a sequencer node visit the sequencer page. Stay up-to-date on Noir and Aztec by following Noir and Aztec on X.
On May 1st, 2025, Aztec Public Testnet went live.
Within the first 24 hours, over 20k users visited the Aztec Playground and started to send transactions on testnet. Additionally, 10 apps launched live on the testnet, including wallets, block explorers, and private DeFi and NFT marketplaces. Launching a decentralized testnet poses significant challenges, and we’re proud that the network has continued to run despite high levels of congestion that led to slow block production for a period of time.
Around 6 hours after announcing the network launch, more than 150 sequencers had joined the validator set to sequence transactions and propose blocks for the network. 500+ additional full nodes were spun up by node operators participating in our Discord community. These sequencers were flooded with over 5k transactions before block production slowed. Let’s dive into why block production slowed down.
On Aztec, an epoch is a group of 32 blocks that are rolled up for settlement on Ethereum. Leading up to the slowdown of block production, there were entire epochs with full blocks (8 transactions, or 0.2TPS) in every slot. The sequencers were building blocks and absorbing the demand for blockspace from users of the Aztec playground, and there was a build up of 100s of pending transactions in sequencer mempools.
Issues arose when these transactions started to exceed the mempool size, which was configured to hold only 100mb or about 700 transactions.
As many new validators were brought through the funnel and started to come online, the mempools of existing validators (already full at 700 transactions) and new ones (at 0 transactions) diverged significantly. When earlier validators proposed blocks, newer validators didn't have the transactions and could not attest to blocks because the request/response protocol wasn't aggressive enough. When newer validators made proposals, earlier validators didn't have transactions (their mempools were full), so they could not attest to blocks.
New validators then started to build up pending transactions. When validators with full mempools requested missing transactions from peers, they would evict existing transactions from their mempools (mempool is at max memory) based on priority fee. All transactions had default fee settings, so validators were randomly ejecting transactions and were not doing so in lockstep (different validators ejected different transactions). For a little over an hour, the mempools diverged significantly from each other, and block production slowed down to about 20% of the expected rate.
In order to stop the mempool from ejecting transactions, the p2p mempool size was increased. By increasing the mempool size, the likelihood of needing to evict transactions that might soon appear in proposals is reduced. This increases the chances that sequencers already have the necessary transactions locally when they receive a block proposal. As a result, more validators are able to attest to proposals, allowing blocks to be finalized more reliably. Once blocks are included on L1, their transactions are evicted from the mempool. So over time, as more blocks are finalized and transactions are mined, the mempool naturally shrinks and the network will recover on its own.
If you are interested in running a sequencer node visit the sequencer page. Stay up-to-date on Noir and Aztec by following Noir and Aztec on X.
When Aztec first got started, the world of zero-knowledge proving systems and applications was in its infancy. There was no PLONK, no Noir, no programmable privacy, and it wasn’t clear that demand for onchain privacy was even strong enough to necessitate a new blockchain network.
After a decade of building, revolutionary breakthroughs in privacy technology have paved the way to, and now set the stage for, mainnet including: PLONK, a novel proving system for user-level privacy and programmability that yielded zk.money and Aztec Connect, which was a pivotal moment for privacy and encryption solutions; Noir, an intuitive zero-knowledge, Rust-like programming language; and a client-side library for a private execution environment (PXE). These tools allow developers to explore privacy-preserving applications across any use case where protecting sensitive data is a critical function.
In 2023 and 2024 Aztec was named by Electric Capital as one of the fastest-growing developer ecosystems. The next generation of applications on Ethereum are already being built using parts of the Aztec stack, like Noir. Projects such as zkPassport and zkEmail are unlocking key identity use cases, while other applications like Anoncast (built in one weekend) have caught the attention of heavyweights like Vitalik Buterin and Laura Shin.
Earlier this month, we announced the successful testing of the first decentralized upgrade process for an L2, with over 100 sequencers participating. Now, with the mission to bring programmable privacy to the masses, the Aztec Public Testnet is here and, for the first time ever, open to developers to build fully private applications on Ethereum.
The Aztec Network will launch fully decentralized from day one.
Not because it’s a flex, but because true privacy can only be achieved when there is no central entity that has potential backdoor access.
Imagine logging into your hot wallet using web2 auth with Google or iCloud, or proving you’re a U.S. citizen onchain without revealing your passport information. For this, you need onchain privacy, and true privacy needs full decentralization so the user can maintain control over their data.
This is the vision for the Aztec Network.
Like Zac, our CEO and Co-founder, said in his talk Privacy: The Missing Link, “there are three fundamental attributes required to bridge the gap and bring the world onchain: interfacing with web2 systems, linking accounts to identities, and establishing digital sovereignty.”
Launching a decentralized network is a complex task filled with lots of intricacies and nuances to navigate. The Aztec Public Testnet plays a crucial role in stress-testing the network, identifying early issues, and ensuring its participants work as intended – ultimately leading to a more robust mainnet.
There are two ways you can participate in the network: as a developer who wants to build and deploy applications (with end-to-end privacy) or as a node operator powering the network.
Aztec enables developers to build with both private and public state.
Smart contracts on Aztec blend private functions that execute on the client side with public functions that are executed by sequencers on the Aztec Network. This allows you to customize your contract with both public and private components while deploying them to a fully decentralized network.
The fastest way to get started with the Aztec Public Testnet is to deploy a smart contract using the Playground. If you’re a developer, visit our dev landing page to connect to Testnet and deploy on the Aztec Network.
The Aztec Network is run by a decentralized sequencer and prover network.
Sequencers propose and produce blocks using consumer hardware and are responsible for proposing and voting on network upgrades. Provers participate in a decentralized prover network and are selected to prove the rollup integrity.
No airdrops. No marketing gimmicks. We just want to create a community of highly skilled operators who share the vision of a fully decentralized privacy-preserving network. Anyone can boot up a sequencer node and access the testnet faucet. See the sequencer quickstart to get started. Apply to get a special Discord role and peer support from experienced node operators leading the Aztec Network.
To see existing applications and get inspo for what you want to build on the Aztec Public Testnet, check out our Ecosystem page. If you’ve already built an app and would like to be featured, submit your app here.
Next, head to the Playground to try out the Aztec Public Testnet, where you can deploy and interact with privacy-preserving smart contracts. Tools and infrastructure to start building wallets, bridges, and explorers are already available.
If you’re a developer, click ➡️ here to get started and deploy your smart contract in literal minutes.
If you’re a node operator, click ➡️ here to set up and run a node.
Stay up-to-date on Noir and Aztec by following Noir and Aztec on X.
Aztec will be a fully decentralized, permissionless and privacy-preserving L2 on Ethereum. The purpose of Aztec’s Public Testnet is to test all the decentralization mechanisms needed to launch a strong and decentralized mainnet. In this post, we’ll explore what full decentralization means, how the Aztec Foundation is testing each aspect in the Public Testnet, and the challenges and limitations of testing a decentralized network in a testnet environment.
Three requirements must be met to achieve decentralization for any zero-knowledge L2 network:
Decentralization across sequencing, proving, and governance is essential to ensure that no single party can control or censor the network. Decentralized sequencing guarantees open participation in block production, while decentralized proving ensures that block validation remains trustless and resilient, and finally, decentralized governance empowers the community to guide network evolution without centralized control.
Together, these pillars secure the rollup’s autonomy and long-term trustworthiness. Let’s explore how Aztec’s Public Testnet is testing the implementation of each of these aspects.
Aztec will launch with a fully decentralized sequencer network.
This means that anyone can run a sequencer node and start sequencing transactions, proposing blocks to L1 and validating blocks built by other sequencers. The sequencer network is a proof-of-stake (PoS) network like Ethereum, but differs in an important way. Rather than broadcasting blocks to every sequencer, Aztec blocks are validated by a randomly chosen set of 48 sequencers. In order for a block to be added to the L2 chain, two-thirds of the sequencers need to verify the block. This offers users fast preconfirmations, meaning the Aztec Network can sequence transactions faster while utilizing Ethereum for final settlement security.
PoS is fundamentally an anti-sybil mechanism—it works by giving economic weight to participation and slashing malicious actors. At the time of Aztec’s mainnet, this will allow sequencers to vote out bad actors and burn their staked assets. On the Public Testnet, where there are no real economic incentives, PoS doesn't function properly. To address this, we introduced a queue system that limits how quickly new sequencers can join, helping to maintain network health and giving the network time to react to potential malicious behavior.
Behind the scenes, a contract handles sequencer onboarding—it mints staking assets, adds sequencers to the set, and can remove them if necessary. This contract is just for Public Testnet and will be removed on Mainnet, allowing us to simulate and test the decentralized sequencing mechanisms safely.
Aztec will also launch with a fully decentralized prover network.
Provers generate cryptographic proofs that verify the correctness of public transactions, culminating in a single rollup proof submitted to Ethereum. Decentralized proving reduces centralization risk and liveness failures, but also opens up a marketplace to incentivize fast and efficient proof generation. The proving client developed by Aztec Labs involves three components:
Once the final proof has been computed, the proving node sends the proof to L1 for verification. The Aztec Network splits proving rewards amongst everyone who submits a proof on time, reducing centralization risk where one entity with large compute dominates the network.
For Aztec’s Public Testnet, anyone can spin up a prover node and start generating proofs. Running a prover node is more hardware-intensive than running a sequencer node, requiring ~40 machines with an estimated 16 cores and 128GB RAM each. Because running provers can be cost-intensive and incur the same costs on a testnet as it will on mainnet, Aztec’s Public Testnet will throttle transactions to 0.2 per second (TPS).
Keeping transaction volumes low allows us to test a fully decentralized prover network without overwhelming participating provers with high costs before real network incentives are in place.
Finally, Aztec will launch with fully decentralized governance.
In order for network upgrades to occur, anyone can put forward a proposal for sequencers to consider. If a majority of sequencers signal their support, the proposal gets sent to a vote. Once it passes the vote, anyone can execute the script that will implement the upgrade. Note: For this testnet, the second phase of voting will be skipped.
Decentralized governance is an important step in enabling anyone to participate in shaping the future of the network. The goal of the public testnet is to ensure the mechanisms are functioning properly for sequencers to permissionlessly join and control the Aztec Network from day 1.
One additional aspect to consider with regard to full decentralization is the role of network users in decentralizing the compute load of the network.
Aztec Labs has developed groundbreaking technology to make end-to-end programmable privacy possible. First with the release of Plonk, and later refinements like MegaHonk, which make it feasible to generate client-side ZKPs. Client-side proofs keep sensitive data on the user’s device while still enabling users to interact with and store this information privately onchain. They also help to scale throughput by pushing execution to users. This decentralizes the compute requirements and means users can execute arbitrary logic in their private functions.
Sequencers and provers on the Aztec Network are never able to see any information that users or applications want to keep private, including accounts, activity, balances, function execution, or other data of any kind.
Aztec’s Public Testnet is shipping with a full execution environment, including the ability to create client-side proofs in the browser. Here are some time estimations to expect for generating private, client-side proofs:
Aztec’s Public Testnet is designed to rigorously test decentralization across sequencing, proving, and governance ahead of our mainnet launch. The network design ensures no single entity can control or censor activity, empowering anyone to participate in sequencing transactions, generating proofs, and proposing governance changes.
Visit the Aztec Testnet page to start building with programmable privacy and join our community on Discord.
When Aztec mainnet launches, it will be the first fully private and decentralized L2 on Ethereum. Getting here was a long road: when Aztec started eight years ago, the initial plan was to build an onchain financial service called CreditMint for issuing corporate debt to mid-market enterprises – obviously a distant use case from how we understand Aztec today. When co-founders Zac Williamson, Joe Andrews, Tom Pocock, and Arnaud Schenk, got started, the world of zero-knowledge proving systems and applications weren’t even in their infancy: there was no PLONK, no Noir, no programmable privacy, and it wasn’t clear that demand for onchain privacy was even strong enough to necessitate a new blockchain network. The founders’ initial explorations through CreditMint led to what we know as Aztec today.
While putting corporate debt onchain might seem unglamorous (or just limited compared with how we now understand Aztec’s capabilities), it was useful, wildly popular, and necessary for the founding team to realized that no serious institution wanted to touch the blockchain without the same privacy assurances that they were accustomed to in the corporate world. Traditional finance is built around trusted intermediaries and middlemen, which of course introduces friction and bottlenecks progress – but offers more privacy assurances than what you see on public blockchains like Ethereum.
This takeaway led to a bigger understanding: the number of people (not just the number of institutions) who wanted to use the blockchain was limited by a lack of programmable privacy. Aztec was born out of the recognition that everyone – not only corporations – could use permissionless, onchain systems for private transactions, and this could become the default for all online payments. In the words of the CEO, Zac Williamson:
“If you had programmable digital money that had privacy guarantees around it, you could use that to create extremely fast permissionless payment channels for payments on the internet.”
Equipped with this understanding, Zac and Joe began to specialize. Zac, whose background is in particle physics, went deep on cryptography research and began exploring protocols that could be used to enable onchain privacy. Meanwhile, Joe worked on how to get user adoption for privacy tech, while Arnaud focused on getting the initial CreditMint platform live and recruiting early members of the team. In 2018, Aztec published a proof-of-concept transaction demonstrating the creation and transfer of private assets on Ethereum – using an early cryptographic protocol that predated modern proving schemes like PLONK. It was a limited example, with just DAI as the test-case (and it could only facilitate private assets, not private identities), but it garnered a lot of early interest from members of the Ethereum community.
The 2018 version of the Aztec Protocol had three key limitations: it wasn’t programmable, it only supported private data (rather than private data and user-level privacy), and it was expensive, from both a computation and gas perspective. The underlying proving scheme was, in the words of Zac, a “Frankenstein cryptography protocol using older primitives than zk-SNARKs.” These limitations motivated the development of PLONK in 2019, a SNARK-based proving system that is computationally inexpensive, and only requires one universal trusted setup.
A single universal trusted setup is desirable because it allows developers to utilize a common reference string for all of the programs they might want to instantiate in a circuit; the alternative is a much more cumbersome process of conducting a trusted setup ceremony for each cryptographic circuit. In other words, PLONK enabled programmable privacy for future versions of Aztec.
PLONK was a big breakthrough, not just for Aztec, but for the wider blockchain community. Today, PLONK has been implemented and extended by teams like zkSync, Polygon, Mina, and more. There is even an entire category of proving systems called PLONKish that all derive from the original 2019 paper. For Aztec specifically, PLONK was also instrumental in paving the way for zk.money and Aztec Connect, a private payment network and private DeFi rollup, which launched in 2021 and 2022 respectively.
The product needs of Aztec motivated the development of a modern-day proving system. PLONK proofs are computationally cheap to generate, leading not only to lower transaction costs and programmability for developers, but big steps forward for privacy and decentralization. PLONK made it simpler to generate client-side proofs on inexpensive hardware. In the words of Joe, “PLONK [was] developed to keep the middleman away.”
Between 2021 and 2023, the Aztec team operated zk.money and Aztec Connect. The products were not only vital in illustrating that there was a demand for onchain privacy solutions, but in demonstrating that it was possible to build performant and private networks leveraging PLONK. Joe remarked that they “wanted to test that we could build a viable payments network, where the user experience was on par with a public transaction. Privacy needed to be in the background.”
Aztec’s early products indicated that there was significant demand for private onchain payments and DeFi – at peak, the rollups had over $20 million in TVL. Both products fit into the vision Zac had to “make the blockchain real.” In his team’s eyes, blockchains are held back from mainstream adoption because you can’t bring consequential, real-world assets onchain without privacy.
Despite the demand for these networks, the team made the decision to sunset both zk.money and Aztec Connect after recognizing that they could not fully decentralize the networks without massive architectural changes. Zac and Joe don’t believe in “Progressive Decentralization” – the network needs to have no centralized operators from day one. And it wasn’t just the sequencer of these early Aztec products that were centralized – the team also recognized that it would have been impossible for other developers to write programs on Aztec that could compose with each other, because all programs operated on shared state. In 2023, zk.money and Aztec Connect were officially shut down.
In tandem, the team also began developing Noir (an original brainchild of Kevaundray Wedderbaum). Noir is a Rust-like programming language for writing zero-knowledge circuits that makes privacy technology accessible to mainstream developers. While Noir began as a way to make it easier for developers to write private programs without needing to know cryptography, the team soon realized that the demand for privacy didn’t just apply to applications on the Aztec stack, and that Noir could be a general-purpose DSL for any kind of application that needs to leverage privacy. In the same way that bringing consequential assets and activity onchain “makes the blockchain real,” bringing zero-knowledge technology to any application – onchain or offchain – makes privacy real. The team continued working on Noir, and it has developed into its own product stack today.
Aztec from 2017 to 2024 can be seen as a methodical journey toward building a fully private, programmable, and decentralized blockchain network. The earliest attempt at Aztec as a protocol introduced asset-level privacy, without addressing user-level privacy, or significant programmability. PLONK paved the way for user-level privacy and programmability, which yielded zk.money and Aztec Connect. Noir extended programmability even further, making it easy for developers to build applications in zero-knowledge. But zk.money and Aztec Connect were incomplete without a viable path to decentralization. So, the team decided to build a new network from scratch. Extending on their learnings from past networks, the foundations and findings from continuous R&D efforts of PLONK, and the growing developer community around Noir, they set the stage for Aztec mainnet.
The fact of the matter is that creating a network that is fully private and decentralized is hard. To have privacy, all data must be shielded cheaply inside of a SNARK. If you want to really embrace the idea of “making the blockchain real” then you should also be able to leverage outside authentication and identity solutions, like Apple ID – and you need to be able to put those technologies inside of a SNARK as well. The number of statements that need to be represented as provable circuits is massive. Then, all of these capabilities need to run inside of a network that is decentralized. The combination of mathematical, technological, and networking problems makes this very difficult to achieve
The technical architecture of Aztec reflects the learnings of the Aztec team. Zac describes Aztec mainnet as a “Russian nesting doll” of products that all add up to a private and decentralized network. Aztec today consists of:
At the network level, there will be many participants in the decentralization efforts of Aztec: provers, sequencers, and node operators. Joe views the infrastructure-level decentralization as a crucial first stage of Aztec’s mainnet launch.
As Aztec goes live, the vision extends beyond private transactions to enabling entirely new categories of applications. The team envisions use cases ranging from consumer lending based on private credit scores to games leveraging information asymmetry, to social applications that preserve user privacy. The next phase will focus on building a robust ecosystem of developers and the next generation of applications on Ethereum using Noir, the universal language of privacy.
Aztec mainnet marks the emergence of applications that weren't possible before – applications that combine the transparency and programmability of blockchain with the privacy necessary for real-world adoption.
