In the world of public blockchains, transparency is a double-edged sword. Ethereum’s open ledger means that every transaction, balance, and smart contract interaction is visible to everyone. While this transparency helps ensure security and trustlessness, it also poses serious privacy challenges. Ordinary users might not want their entire financial history exposed to the world, and businesses can be reluctant to use a network where competitors or strangers can scrutinize their on-chain activities. In short, the lack of privacy on traditional blockchains has become a glaring obstacle for broader adoption and sensitive use cases.

Aztec Network emerges as a solution to this problem by introducing privacy as a first-class feature on Ethereum. Aztec is a Layer 2 blockchain (or “rollup”) built on Ethereum that enables smart contracts with both private and public execution. In essence, it allows users and developers to choose what information stays confidential and what remains transparent. Aztec accomplishes this through a hybrid public-private architecture: part of a transaction can run in a private context known only to the user, and part can run publicly like a normal Ethereum transaction. Under the hood, advanced cryptography – in particular, zero-knowledge proofs – ensures that even though some data is hidden, all transactions are still valid and follow the rules. As a zkRollup, Aztec batches many transactions together and submits a succinct proof to Ethereum, inheriting Ethereum’s security and consensus. This means users get both the security guarantees of the Ethereum mainchain and a new layer of privacy on top. What follows is a deep dive into how Aztec achieves “encrypted execution,” the architecture that powers it, the use cases it unlocks, and how it compares to other approaches to blockchain privacy.

Zero-Knowledge Proofs and Encrypted Execution Basics

Zero-knowledge proofs are the key technology that make Aztec’s brand of private execution possible. A zero-knowledge proof (ZKP) allows one party to prove to another that a statement is true, without revealing why it’s true or any of the underlying data. In the context of blockchains, a specialized form called a zk-SNARK (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge) is often used. zk-SNARKs let a user prove, for example, “I have a valid transaction that follows all the rules,” without revealing the transaction’s details (like sender, receiver, or amounts). These proofs are succinct (very small and quick to verify) and non-interactive (no back-and-forth communication is needed), making them practical to use on-chain. The concept of using zk-SNARKs for privacy was pioneered by projects like Zcash, where they hide the details of money transfers. Aztec extends this idea to general smart contract logic: users can prove that they executed complex contract code correctly, without exposing the inputs, outputs, or internal state of that code.

Beyond privacy, zero-knowledge proofs also enable scalability through zkRollups. A rollup is a Layer 2 mechanism that processes many transactions off the main chain and then posts a summarized result back to the main chain. In a zkRollup, that summary is a validity proof (a zk-SNARK) attesting that all the off-chain transactions were valid. This approach greatly reduces load on the main chain: instead of every transaction being replicated on Ethereum, only a single proof and some minimal data need to be posted for a whole batch of transactions. Ethereum’s consensus verifies the proof, which is much cheaper than executing all those transactions natively. The result is a big increase in throughput and lower fees, all while maintaining security. Aztec leverages this same rollup principle – meaning users’ transactions are bundled and verified by proof – but crucially, it also uses the zk proofs to hide information. In other words, Aztec’s rollup is not just about scaling, but about scaling with privacy. The proof that goes to Ethereum confirms the correctness of many transactions without revealing their private details to the world.

Achieving privacy on a blockchain requires rethinking how state (data) is managed. Public blockchains like Ethereum use an account model: each account has balances and variables that get updated openly. In a private system, an account model is problematic because any change would reveal something (like a balance going up or down). Aztec and similar systems instead use a note-based UTXO model for private state. You can think of notes as encrypted tokens or records – similar to the unspent transaction outputs (UTXOs) in Bitcoin, but hidden. A note might represent, for example, “Alice has 50 tokens,” but instead of that being an entry in a public ledger, it’s encoded as a cryptographic commitment (a piece of data that hides the value and recipient). All these commitments are stored in a Merkle tree (an append-only structure on the Aztec Layer 2) so that their existence and consistency can be efficiently verified, but their contents remain encrypted. When Alice wants to send those 50 tokens to Bob, she doesn’t simply decrement and increment balances as on Ethereum. Instead, she spends her note and creates a new note for Bob. Spending a note means producing a zero-knowledge proof that she knows the secret values of a valid existing note and wants to invalidate it. To prevent double-spending of the same note, Aztec uses nullifiers – basically, unique identifiers for notes that have been spent. When Alice spends her note, the system publishes a nullifier (in a separate nullifier Merkle tree) corresponding to that note, so no one can ever spend it again. Importantly, the nullifier does not reveal which note was spent; it’s just a cryptographic fingerprint. Meanwhile, Alice’s transaction also includes Bob’s new encrypted note (for 50 tokens to Bob). This new note is added to the commitments tree. The zero-knowledge proof ties it all together: it proves that some valid note was consumed and new notes were created that preserve the total value, all according to the rules of the token contract – without revealing actual amounts or addresses. In summary, Aztec’s private state model is all about hiding actual data behind commitments, and using proofs plus nullifiers to enforce the rules and prevent abuse.

One crucial consequence of this design is that much of the work to create a transaction must happen on the client side (the user’s own device). In a traditional blockchain like Ethereum, the network’s nodes execute your transaction (running your smart contract code) publicly. But in Aztec’s case, if you want to do something privately – say run some contract logic on hidden inputs – the network cannot do it for you, because that would require exposing your secrets. Instead, encrypted execution means the user does the heavy lifting. Your Aztec wallet (or application) will locally run the private portions of the smart contract, using your private data, and generate a proof that the computation was carried out correctly. This is often called client-side proving, and it’s a cornerstone of Aztec’s approach. Once the proof is generated, it is submitted to the Aztec network along with any public-facing outputs of the transaction (for example, “call this public function X with these public parameters, and here’s a proof that the prior private steps were valid”). The Aztec nodes can then quickly verify the proof without ever seeing your secret info. In effect, execution is happening in an encrypted bubble on the user’s side, and only a cryptographic certification of that execution reaches the blockchain. This allows encrypted smart contract execution: contracts can have private state and private logic, yet anyone can verify later that everything was done correctly according to the contract’s rules. The data stays confidential, but the integrity is guaranteed by math. This general model – combining zero-knowledge proofs, a note-based state, and client-side proving – is what makes Aztec a truly privacy-preserving platform rather than just a simple mixer. With the fundamentals established, we can now explore how Aztec implements these ideas in practice.

Aztec’s Hybrid Architecture: Combining Private and Public Execution

Building a full-featured Layer 2 that supports both private and public transactions is a complex balancing act. Aztec’s architecture achieves this by cleanly separating the network into two execution realms: one private and one public, and then coordinating between them. At a high level, every Aztec transaction begins in the Private Execution Environment (PXE) on the user’s device and may end in the Aztec Virtual Machine (AVM) on the network’s nodes. The two environments handle different parts of the transaction, and together they form a seamless hybrid execution model.

Here’s how a typical transaction flows: A user initiates an Aztec transaction through a wallet or dApp interface (using a library like Aztec.js, analogous to web3.js on Ethereum). Suppose this transaction involves some private logic – for example, transferring a hidden amount of a token, or invoking a confidential section of a smart contract. The first step happens on the user’s side in the PXE. The Private Execution Environment is essentially a sandbox within the user’s wallet software that can execute private functions of smart contracts. These private functions are written in a way that they can run with encrypted inputs and produce outputs plus a proof. The PXE uses the user’s private keys and notes to simulate the contract’s execution locally. All the modifications to private state (like creating or nullifying notes) are handled here. The outcome of this private execution is a set of encrypted state updates (new notes, new nullifiers) and a zero-knowledge proof attesting that the execution was correct according to the contract’s rules. Crucially, this proof covers the private function’s logic – meaning the network never needs to rerun those steps.

Once the PXE finishes, the transaction isn’t done yet. A private function can schedule or trigger a public function as part of the same transaction. For example, a private transfer might have a public component such as emitting a public event, updating a publicly visible counter, or interacting with a public liquidity pool. After the PXE produces the proof and the intended public call, it hands off control to the network. The encrypted state updates (the new note commitments, nullifiers, etc.), along with the proof and the call to any public function, are sent to the Aztec Layer 2 network. Here is where the Aztec Virtual Machine (AVM) comes into play. The AVM, running on Aztec nodes, is the public smart contract execution environment – conceptually similar to Ethereum’s EVM. It will take the transaction, verify the accompanying proof (ensuring the private part was valid), and then execute the specified public functions using normal blockchain logic. Public functions in Aztec behave much like Ethereum smart contract calls: they can update public state, log events, call other contracts, and so on, except they operate within Aztec’s rollup environment. Because the proof has already validated the private part, the AVM can safely act on whatever public actions were requested, knowing they are authorized and consistent with the hidden state. It’s important that the flow is one-directional: a private function can call a public function later in the same transaction, but a public function cannot invoke a private one. This rule ensures that no public contract ever pauses and waits for secret data (which would break the model). All private computation must be completed and proven before public execution begins.

The division between PXE and AVM means that Aztec effectively has two worlds running in parallel: the client-side private world and the network’s public world. Interestingly, these two do not directly talk to each other during execution – the hand-off happens only via the proof and the data the user chooses to output. The PXE doesn’t get to query the AVM state during its run (it wouldn’t even make sense, since the AVM state is on the nodes), and conversely, the AVM has no direct insight into what happened inside the PXE beyond what the proof and the resulting data reveal. This separation is by design, to maintain a strong privacy boundary. If private and public parts need to interact, they must do so in a controlled manner (private passing data to public in the form of committed outputs or public function calls with parameters). For example, a private function could produce an encrypted note that a public function then marks as registered in some public registry, without the public function ever seeing what’s inside the note.

Underneath this execution model, Aztec manages a hybrid state consisting of both private and public components. All the private state – those encrypted notes we discussed – live in Aztec’s off-chain data structures (commitment trees and nullifier trees). When the user’s PXE creates new notes or nullifiers, those are eventually incorporated into these trees maintained by the Aztec network. Meanwhile, any public state (analogous to normal contract storage variables or account balances in a typical blockchain) is maintained in a separate state tree that functions like Ethereum’s world state. Aztec basically operates with two parallel state databases: one encrypted, one transparent. This allows Aztec smart contracts to have some variables or assets kept hidden and others exposed. For instance, consider a decentralized exchange built on Aztec: it could keep user positions and trade amounts private (as notes), but still maintain a public running total of liquidity in the pool for transparency, or a public price feed. The contract might use private functions for trade execution (so individual trades are confidential), and a public function to update a public price or accounting metric. Thanks to the hybrid state model, developers can decide the privacy level of each piece of state. Data that doesn’t need to be public can be shielded as notes, and data that benefits from transparency or interoperability can be left in public state. Both kinds of state transitions are rolled up into the same block and secured by the same proofs. It’s a flexible design that gives granular privacy control – not everything is forced to be private or public, but can be mixed as appropriate.

Because Aztec is a privacy-first system, even the notion of user accounts is adapted to fit. Aztec employs native account abstraction, meaning every user’s “account” is actually a smart contract rather than a simple key pair. This is different from Ethereum’s base layer where an Externally Owned Account is just a key that signs transactions. In Aztec, your account is a contract that defines how you authorize actions and manage your keys. This was a deliberate choice: it allows much more flexibility in a privacy context. For example, an Aztec account contract could require multiple signatures (multi-sig) to approve a spending – a useful feature for security – or could implement social recovery (where trusted parties can help regain access if you lose keys), all without any centralized provider. Account abstraction also means paying transaction fees (often called gas fees) can be done in novel ways; an account could be set up to let a third-party pay fees on the user’s behalf (gasless transactions) or to automatically swap some tokens to pay fees. These schemes are possible because the logic is in a customizable contract. Each Aztec account actually manages several cryptographic key pairs behind the scenes. Notably, there are distinct keys for different roles: one key pair is used to derive nullifiers (so that only the owner can nullify their notes), and others are used as viewing keys for encryption. Specifically, Aztec uses an incoming viewing key and an outgoing viewing key – these allow the recipient and sender of a note, respectively, to decrypt the note’s contents. The network itself never sees plaintext note data, but the intended recipients can decrypt and use their notes via these keys. Unlike a typical blockchain account, an Aztec account doesn’t automatically have a single signing key; instead, the account contract decides what authorizes a transaction. This means from the protocol’s perspective, a user proves validity of actions via ZK proofs and whatever signature scheme their account expects. All these design choices ensure that adding privacy doesn’t come at the cost of usability or security – users can still have rich security models for their accounts and devs can design how identity and authorization work in their applications.

For developers, Aztec provides tools to make building these private applications easier. Central to this is Noir, Aztec’s open-source domain-specific language for writing zero-knowledge programs. Noir was created to let developers express both the private and public parts of their dApps in a straightforward way, without needing a PhD in cryptography. It has a syntax similar to Rust, a familiar, modern programming language, and it compiles into an intermediate form that can then be turned into efficient zk-SNARK circuits. Importantly, Noir is platform-agnostic – it isn’t strictly tied to Aztec’s proving system and could target other proving backends as well – but Aztec uses it as the primary language for writing contracts. With Noir, a developer can write a smart contract and designate certain functions as private or public. Private functions will be executed in the PXE (and automatically generate proofs), while public ones run in the AVM. The language and its compiler handle a lot of the heavy lifting, like constraint generation and circuit optimization, so the programmer can focus on business logic. For example, if you’re creating a confidential voting contract, you might write a private function for casting a vote (which takes a secret ballot and outputs a encrypted tally update plus a proof), and a public function for finalizing the vote result (which might read the now-aggregated result and publish it). Noir allows you to write this in a high-level way, and it will produce the circuits needed to enforce it. By providing a familiar development experience and integrating with Ethereum-like tooling (such as Hardhat and Typescript libraries), Aztec lowers the barrier for developers to create programmable privacy applications. They can use concepts they know from Ethereum (events, functions, state variables), augmented with the ability to make some of those private. This means mainstream developers can start building on Aztec without mastering elliptic curve arithmetic or cryptographic hash functions – the platform handles that complexity.

Behind all these features, Aztec’s performance and security rely on cutting-edge cryptography. The network uses a proving system from the PLONK family of zk-SNARKs. (In fact, Aztec’s founders were co-inventors of the original PLONK protocol in 2019.) PLONK is a powerful proof system known for its universal setup (one trusted setup ceremony can support any program, rather than needing one per circuit) and for efficiencies that have been improved over time (through variants like TurboPLONK, UltraPLONK, etc.). Aztec’s latest iteration incorporates further innovations to reduce the cost of generating proofs on ordinary hardware. For example, they have developed techniques like recursive proofs (where many proofs are compressed into one final proof) to aggregate transactions efficiently, and a method whimsically nicknamed “Goblin Plonk” to speed up proof generation for user devices. The result is that even though each user might be doing heavy computation to prove their transaction, the overhead is kept manageable, and it’s expected to only get faster as the technology and hardware improve. On the network side, by verifying one aggregate proof per block, Aztec dramatically lowers the cost per transaction compared to verifying each transaction individually on Ethereum. It’s worth noting that privacy does introduce some extra data overhead – encrypted notes and nullifiers have to be published (in encrypted form) to the Ethereum base layer for safety, which means Aztec blocks carry more data than a purely transparent rollup might. This can make transactions a bit larger in bytes, and thus slightly more expensive in terms of Ethereum fees, than if everything were public. However, Ethereum’s roadmap (with proposals like data shards and EIP-4844 “proto-danksharding” introducing cheaper data blobs) is actively addressing the cost of rollup data. In the long run, Aztec expects to benefit from these improvements, making private transactions nearly as cheap and fast as regular Layer 2 transactions. In the meantime, users are essentially paying a small premium for privacy – a trade-off many are willing to make for the added confidentiality. And crucially, Aztec maintains the trustless nature of blockchains: the security comes from math and code, not from trusting any intermediary. Even the Aztec sequencers (the nodes bundling transactions) cannot break the privacy or forge invalid transactions; if they try, their proofs would fail and Ethereum would reject the batch. In summary, Aztec’s architecture marries a novel private execution flow with proven public blockchain techniques, resulting in a Layer 2 network where encrypted and transparent operations coexist. This opens the door to a realm of new possibilities on Ethereum.

Why a Private Layer 2? – Rationale and Use Cases

The motivation for Aztec Network becomes clear when you consider all the applications that have been impractical or unsafe on a fully public blockchain. Blockchains to date have been sometimes described as glass ledgers or even digital panopticons – all activities are out in the open. While this radical transparency is acceptable for certain use cases (for instance, trading funny cat NFTs or showcasing the provenance of a piece of art), it is unacceptable for many real-world scenarios. Privacy isn’t just a “nice-to-have” feature; in many cases it’s a requirement for the application to make sense at all. By providing a privacy-preserving Layer 2, Aztec aims to unlock these scenarios, bringing a wider class of users and businesses into the blockchain space. Let’s explore a few domains where Aztec’s hybrid approach is especially potent:

Decentralized Finance (DeFi) is one of the clearest examples. DeFi has thrived on Ethereum, but it has inherited Ethereum’s transparency. This means that anyone can spy on large traders’ moves, copy their strategies, or front-run their trades (a practice where bots monitor the mempool and jump ahead of large orders to profit at the expense of the original trader). Such activities harm honest users and would be outright illegal in traditional finance due to the unfair advantage gained. With Aztec, DeFi applications can be designed to preserve confidentiality for traders and investors. For instance, a user could trade or lend money without publicly revealing the size of their position or even the identity of the asset until after settlement. Competitors and opportunists wouldn’t be able to track a fund’s every move on-chain, which in turn reduces the risk of exploitation and encourages more participation. Privacy in DeFi also means personal financial data stays personal; your loan history or portfolio balance need not be an open book to anyone with a blockchain explorer. Beyond trading, think of private auctions or sealed-bid transactions where bids are hidden until an outcome is decided – these become possible on Aztec, leveling the playing field. In a nutshell, Aztec enables a fairer and more secure DeFi environment, where strategies cannot be countered in advance and user activity doesn’t broadcast financial secrets to the world.

Enterprise and institutional use cases are another huge area. Companies have been interested in blockchain for things like supply chain management, inter-bank settlement, and record-keeping, but they face an obvious hurdle: they can’t put sensitive business data on a public ledger for all to see. From a corporation’s perspective, an Ethereum transaction that discloses who its partners are, what its supply shipments contain, or how it allocates funds is a non-starter. Aztec’s privacy features allow businesses to use an Ethereum-secured network while keeping proprietary or personal data encrypted. For example, consider a supply chain scenario: a company could tokenize goods and track ownership transfers on Aztec. Each transfer could be a private transaction, so only the relevant parties know the details (quantity, price, origin/destination), while an outside observer might see only that a valid transfer occurred. Auditors or regulators could be given viewing keys or selective access if needed, but the public wouldn’t get to see the entire operation. Similarly, financial institutions could settle trades or payments via Aztec in a way that rivals cannot monitor their positions or strategies. Even something as common as payroll can benefit: a business could pay employees in stablecoins on Aztec, ensuring that salary amounts remain confidential (preventing employees or outside observers from comparing paychecks), yet the company could still prove to auditors that correct payments were made. Aztec essentially enables enterprise-grade confidentiality on top of a public blockchain – something enterprises require for comfort. Notably, because Aztec is an open system, multiple organizations can transact on the same network without trusting each other, and still maintain privacy. This is far more powerful than a closed consortium chain because it inherits the public Ethereum’s security and interoperability while offering privacy. We are likely to see applications like confidential trading platforms, private asset issuance (e.g. a private bond or equity token only revealed to authorized investors), and shielded data marketplaces emerge on Aztec. Even governments or public sector projects could use it for things like confidential voting or private registries, where transparency to the general public is not desired.

Digital identity and personal data management stand to gain immensely from a privacy-preserving platform like Aztec. One can build identity systems where individuals control their own credentials and selectively disclose information. For instance, a user could prove to a dApp or another user that they are over 18, or that they have a certain certification or membership, without disclosing their actual identity or any extra personal details. Using zero-knowledge proofs, an Aztec application could verify a condition (like “Alice has a valid driver’s license issued by X”) privately. While Ethereum alone could also verify credentials with ZK proofs, doing so on Aztec means the verification process itself can be kept off the public record – preserving the privacy of the person’s data. Another example is private voting and governance. DAOs (decentralized autonomous organizations) might want secret ballots so that small voters aren’t pressured by large holders or so that vote outcomes aren’t influenced by observing interim results. On Aztec, one could implement a voting contract where votes are encrypted notes. Each vote cast would be a private transaction (with a proof that it’s a valid vote by an eligible voter), and the tally could be revealed at the end by a public function that only shows the final aggregate result. This way, the sanctity of a secret ballot is preserved on-chain. Credential verification, private KYC, secure messaging, and even health record attestation are all feasible use cases—essentially, any situation where you want to use the blockchain as a source of truth or coordination platform, but don’t want to expose sensitive personal information to everyone. Aztec’s design means you can prove things about data without revealing the data itself, and only share it with those who need to know.

Even the world of gaming and NFTs can benefit from Aztec’s capabilities. Blockchain gaming has introduced concepts like true ownership of in-game assets (via NFTs) and transparent game logic, but full transparency can ruin certain types of games. Consider strategy games or card games: if every move or every card is on a public ledger, there’s no mystery – anyone could look up all players’ hands or strategies. With Aztec, game developers can keep parts of the game state hidden. For example, an on-chain card game could represent each card as a note (so only the owner knows which card it is, perhaps via a viewing key, and others just see an encrypted blob). Players could make moves that are privately validated (ensuring they follow the rules and actually possess the card they claim, etc.) without exposing the card’s face until it’s played. This opens up the possibility for entirely on-chain games with hidden information, which was previously impossible. Additionally, NFTs could carry private metadata – imagine an NFT artwork where only the owner can see the full-resolution image or unlock special content, while everyone else just sees a limited preview or nothing at all. Or an NFT representing a secret that only the holder can decrypt. These kinds of mechanics become much more straightforward on a platform that natively supports encryption and selective disclosure. Furthermore, by hiding certain attributes, you could prevent issues like sniping or discrimination in NFT markets (for instance, hidden traits in an NFT mint so that all tokens are bid on more fairly without knowing if they’re “rare” or not until after purchase). Overall, Aztec can add a layer of surprise and confidentiality to blockchain games and collectibles, enabling richer experiences.

The broader rationale for a private L2 like Aztec is to bring blockchain technology to parity with real-world expectations of privacy. In everyday life, we choose what to share and what to keep private. We might happily publish some information on social media, but we keep our bank account details, salaries, and personal communications confidential. Traditional digital systems provide various access controls, but when you move into the realm of decentralized blockchain, up until now it’s been largely all-or-nothing: either put data on a public ledger or keep it entirely off-chain. Aztec offers a middle path – data can live on-chain (meaning it’s secured by Ethereum and can interact with smart contracts) but in an encrypted form so that only those permitted can see it. This has huge implications. It means that sectors like finance, enterprise operations, identity, healthcare, and gaming can potentially enjoy the benefits of blockchain (like disintermediation, trustless verification, and global reach) without the deal-breaker of exposing sensitive information. Moreover, Aztec’s selective privacy means it’s not about hiding everything by default, but letting developers and users choose what to keep private and what to make public. This flexibility might also help satisfy regulatory concerns – for instance, a financial application on Aztec could keep customer data private from the public, yet still allow an auditor or regulator to verify transactions when necessary by sharing specific decryption keys or using view access mechanisms. It’s a far cry from the stereotype that “privacy coin = shady activity.” Instead, it’s about practical privacy for legitimate use cases. By enabling this, Aztec is expanding Ethereum’s utility into areas that previously were off-limits, thereby driving the next generation of adoption where users don’t have to sacrifice their confidentiality to participate in Web3.

Comparisons with Other zkRollups and Privacy Solutions

To better understand Aztec’s niche, it’s helpful to compare it with other projects in the blockchain space that tackle scalability or privacy. Aztec is unique in combining programmable privacy with Ethereum compatibility, but there are other solutions each addressing parts of this puzzle. Below is a comparison with a few categories of existing technologies, highlighting how Aztec differs:

• Privacy Coins (e.g. Zcash, Monero): Traditional privacy-focused cryptocurrencies like Zcash and Monero provide strong privacy for simple transactions (sending and receiving funds), but they are not programmable in the way Ethereum or Aztec is. Monero uses cryptographic techniques to hide transaction details (amounts, sender, receiver) and is great for private transfers of its native coin, but it doesn’t support general smart contracts at all. Zcash does allow private transfers of its coin using zk-SNARKs and has limited scripting, but again, you can’t build complex decentralized applications on Zcash. Aztec, by contrast, offers privacy and full smart contract capabilities. It effectively extends the guarantees of systems like Zcash to a platform where developers can create custom logic and dApps. With Aztec, one can build private lending protocols, confidential voting systems, or any number of applications that Zcash/Monero simply can’t support due to their limited scope. In short, Aztec aims to be to Ethereum what Zcash is to Bitcoin – and then go further by enabling entire private dApp ecosystems. It’s like having the privacy of Zcash/Monero inside a flexible smart contract world.

• Other zkRollups (e.g. zkSync, StarkNet): A number of Layer 2 projects use zero-knowledge proofs to scale Ethereum, such as zkSync, Polygon Hermez (zkEVM), StarkNet, and others. These zkRollups focus on throughput and cost reduction by batching transactions with validity proofs, but privacy is not their primary goal. In fact, most current zkRollups still execute transactions in a fully transparent manner – everyone can see the contents of those L2 transactions, just like on Ethereum, even though the proof is used to compress them. The “zk” in their name refers to the validity proofs (for scalability), not to hiding data. If they include any privacy at all, it’s minimal or optional and often not built into the core design. Aztec is fundamentally different because it is privacy-first. Its entire architecture (the private execution, notes, etc.) is built around hiding data by default. For example, zkSync or StarkNet might allow faster or cheaper trades, but everyone can still watch those trades and trace addresses on those platforms. On Aztec, someone could use a DeFi app and outsiders would not see the specifics of that activity. Additionally, Aztec introduces features like encrypted state and client-side proving that other rollups don’t have, since those features aren’t needed if you aren’t doing private execution. This does mean Aztec’s design is more complex and geared toward privacy use cases. In comparison, other zkRollups aim to be as close to Ethereum (public) as possible for easier deployment of existing contracts (like deploying an existing Solidity contract on a zkEVM). Aztec takes a different path by creating a new execution model to enable privacy. So, while Aztec still benefits from scalability via zk proofs, its competitive edge is offering privacy and confidentiality options that general-purpose rollups don’t natively offer.

• Ethereum Mixing and Privacy Tools (e.g. Tornado Cash, Railgun): Before Aztec, if Ethereum users wanted privacy, they often resorted to mixers like Tornado Cash or layer-1 add-ons like the Railgun contract. Tornado Cash allows a user to deposit ETH or ERC-20 tokens into a smart contract and then later withdraw them to a different address, breaking the link between sender and receiver – but it’s limited to that one functionality (and has faced regulatory issues). It doesn’t support arbitrary smart contract interactions; you can’t privately use the funds in a DeFi app directly from Tornado without revealing yourself. Railgun is a smart contract system on Ethereum that uses zk-SNARKs to allow private transfers and trades within a shielded pool, offering something closer to Aztec’s note system but on the main layer. However, doing this on L1 Ethereum is extremely costly in terms of gas, and it’s not integrated as a general platform for building any dApp – it’s more of a specific privacy overlay. Aztec differs by being a full Layer 2 network rather than a single contract or mixer. It provides ongoing private state: you can hold assets privately on Aztec, use them in various applications privately, and continue to operate without coming out of the shielded pool. In Tornado, once you withdraw, your coins are “public” again; in Aztec, you could keep them private indefinitely and use them across many apps. Aztec’s privacy is also composably integrated into apps, not an afterthought. This means you could have one private transaction feed into another contract and so on, all under the umbrella of the Aztec system. Mixer solutions don’t allow this kind of complex interaction – they’re one-off privacy tricks. Additionally, Aztec maintains Ethereum compatibility, so you can move assets in and out from Ethereum (like bridging) when needed, but while they are inside Aztec, they can be transacted with confidentiality. Another way to put it: mixers hide one specific action (like transferring funds from A to B), whereas Aztec enables building an entire private economy or application ecosystem on Ethereum’s foundation. It’s a much more powerful and general privacy solution than earlier Ethereum privacy tools.

• Unique Combination of Privacy and Programmability: What really sets Aztec apart is that it blends features that previously were siloed in different projects. It has the privacy strength of a Zcash-like system, the flexibility of Ethereum’s smart contracts, and the scalability of a modern rollup. No other solution currently offers all three together on Ethereum. Some projects use secure hardware (TEE enclaves like on Secret Network) to get private smart contracts, but that involves trusting hardware manufacturers and doesn’t use zero-knowledge cryptography – Aztec opts for a purely cryptographic approach without needing special hardware. Other experimental systems might enable private computation but require a completely new chain or compromise on decentralization. Aztec is aiming for a fully decentralized, Ethereum-integrated network where confidentiality is a fundamental feature. It’s also important to note the selective disclosure capability Aztec brings: developers and users can decide what to keep private and what to reveal. This is more nuanced than, say, Monero where everything is private but you also lose some functionality, or Ethereum where nothing is private. Aztec lets you toggle the privacy knobs as needed. This granular control is unique, as it allows applications to be compliant or transparent in the ways they need while still shielding sensitive details. In summary, Aztec’s hybrid execution and state model create possibilities that none of the existing privacy coins, rollups, or mixers alone can achieve. It represents a fundamental advancement in blockchain architecture: an environment where data can remain encrypted and confidential by default, but the network can still universally verify and enforce rules. That combination – private data with publicly verified correctness – is Aztec’s special sauce in the competitive landscape.

Conclusion

Aztec Network represents a significant evolution in blockchain technology, as it tackles one of the space’s most long-standing limitations: the lack of privacy. By weaving zero-knowledge proofs and encrypted execution into a Layer 2 rollup, Aztec shows that we don’t have to accept an all-or-nothing choice between transparency and confidentiality. Users and developers can have both the security and openness of Ethereum and the privacy of a shielded system. This is a big deal for the future of decentralized applications. Many potential blockchain applications – from banking and trading to healthcare and governance – have been kept at bay by concerns that putting data on-chain would expose too much. Aztec provides a path forward for those applications, allowing sensitive data to stay hidden without sacrificing the trustless, decentralized nature of the blockchain.

Technically, Aztec’s achievement is in combining multiple advanced components into one coherent platform. It demonstrates that zero-knowledge proofs are not just a theoretical tool or a niche feature for private transactions, but a practical foundation for a general-purpose blockchain layer. It also proves that privacy and programmability can coexist: developers can write rich dApps that users can interact with privately. This opens the door for new kinds of dApps that were previously unimaginable on a public ledger. For example, we might soon see decentralized exchanges where you can trade without revealing your entire order book to the world, or social dApps where your interactions are private by default but verifiable when needed. Moreover, Aztec does all this while remaining anchored to Ethereum, meaning it benefits from Ethereum’s security, its bustling ecosystem of developers and tools, and its broad user base. Assets can flow between Aztec and Ethereum mainnet, and eventually even between Aztec and other Layer 2s or L1s, creating a universe where privacy-enhanced applications live alongside public ones seamlessly.

From a broader perspective, Aztec’s approach could become essential infrastructure for a more inclusive and secure Web3. It’s a step toward bringing real-world privacy expectations into blockchain, which could make ordinary users and large organizations more comfortable with using these technologies. If successful, Aztec Network will allow people to enjoy financial services, games, social platforms, and more on Ethereum without broadcasting their personal information to everyone. It also sets a precedent and template for other projects – inspiring the idea that perhaps all Layer 2s and future blockchains should consider privacy as a core design principle, not an afterthought. Of course, Aztec is still in its early stages (as of writing, it’s in public testnet and gearing up for mainnet). Challenges remain, such as further improving proving efficiency, decentralizing the network’s operator set, and navigating the regulatory landscape for privacy tech. Yet, the progress so far – including successful demonstrations of private DeFi interactions and thousands of users testing the network – is a strong proof-of-concept that the technology works.

In conclusion, Aztec Network is pushing the boundaries of what’s possible in blockchain by delivering a platform where users don’t have to choose between blockchain’s power and their own privacy. It validates the idea that confidentiality can coexist with transparency in a controlled, intentional way. As Aztec matures, it could fundamentally reshape how we think about on-chain applications: instead of the default being “everything is public forever,” we could move to a model where privacy is normal and leaks of information are the exception. That paradigm shift would bring blockchain technology much closer to the way society operates in other domains – private by default, public by choice – potentially unlocking a wave of new use cases. For crypto enthusiasts and developers alike, Aztec’s rise is an exciting development, showing that the next generation of blockchain innovation will empower users with more control over their data. The era of the fully public ledger may soon give way to an era of programmable privacy, and Aztec Network is at the forefront of this transformation.