Aztec Connect

Aztec Connect was a Layer 2 privacy solution that functioned as a bridge and batching mechanism. It allowed users to conduct private transactions—where amounts and recipient addresses were concealed—while still interacting with popular public DeFi protocols like Lido, Uniswap, and Curve. This was achieved by aggregating user intents, executing them efficiently on Ethereum's mainnet via a single contract called the Bridge Contract, and then settling the private outcomes back on Aztec's zk-rollup. The core technology was zero-knowledge proofs (ZKPs), specifically zk-SNARKs, which cryptographically verified transactions without revealing underlying data.

The protocol's architecture relied on a network of bridges, each a smart contract programmed for a specific DeFi protocol's logic. A user would initiate a private transaction on Aztec's rollup, which was then relayed to the appropriate bridge contract on Ethereum. This bridge would batch the transaction with others, execute the public trade or action, and submit a validity proof. This design meant users could privately provide liquidity, swap assets, or earn yield, with the public blockchain only seeing a single, aggregated transaction from the bridge, effectively anonymizing the individual participants.

A key innovation was cost efficiency. By batching hundreds of private actions into a single public Ethereum transaction, Aztec Connect dramatically reduced the gas fee burden for each user, making private DeFi economically viable. Furthermore, it offered composability, as the private assets settled on Aztec's rollup could be used in subsequent, more complex private transactions within the Aztec network, enabling a full suite of confidential financial applications.

Aztec Connect was deprecated in March 2024 as its development team, Aztec Labs, shifted focus to Aztec, a new general-purpose, privacy-focused zk-rollup. While Connect served as a pioneering hybrid privacy model, the new Aztec architecture aims to provide a more flexible and developer-oriented platform for building fully private smart contracts, moving beyond the bridge-based model to native privacy for all on-chain interactions.

Aztec Connect is a Layer 2 (L2) privacy infrastructure that allows users to interact with public Ethereum DeFi applications—such as Uniswap, Lido, or Aave—while keeping the details of their transactions private. It functions as a privacy bridge, where user funds are deposited into a smart contract called a rollup processor on the Aztec network. Users can then submit private transactions, which are batched together and proven with zero-knowledge proofs before being settled on Ethereum's Layer 1. This architecture separates the private computation (on Aztec) from the public execution (on mainnet), enabling privacy for actions like swapping or lending.

The core mechanism relies on a client-side proving system. When a user wants to perform a DeFi action, their Aztec wallet locally generates a zero-knowledge proof, known as a ZK-SNARK, that validates the transaction without revealing the sender, recipient, or amount. These private intents are aggregated into a single batch by a sequencer. The batch proof is then submitted to Ethereum, where the connected DeFi protocol executes the net result of all the batched transactions—for example, a single large trade on Uniswap—while the individual user's involvement remains completely confidential on-chain.

A key component is the bridge contract, a smart contract deployed on Ethereum for each supported DeFi protocol. This contract acts as a trusted intermediary: it receives the aggregated, anonymized instructions from the Aztec rollup processor, interacts with the target protocol (e.g., performing a swap), and returns the resulting assets to the Aztec contract. Users ultimately receive their private notes representing the new asset balance within the Aztec network. This design means public liquidity pools never see individual private users, preserving privacy without requiring protocols to modify their own code.

The final piece is fee abstraction. To maintain privacy, transaction fees are also handled confidentially. Users pay fees in the asset they are transacting with, and these fees are aggregated and paid by the bridge contract in the public settlement. This prevents fee payment from becoming a privacy leak. Aztec Connect demonstrated a scalable model for private DeFi, though the original Aztec Connect system was deprecated in March 2024 with the launch of Aztec 3.0, which introduced a fully programmable, general-purpose zkRollup for private smart contracts.

Aztec Connect was a Layer 2 privacy solution built on Ethereum that functioned as a bridge between private transactions and public DeFi protocols. It utilized zero-knowledge proofs, specifically zk-SNARKs, to enable users to interact with applications like Lido, Uniswap, and Curve through a single, private transaction. The core innovation was its rollup architecture, which aggregated many private actions into a single, verifiable proof that was settled on the Ethereum mainnet, significantly reducing gas costs while maintaining privacy.

The protocol's architecture was built around two main components: the Aztec Connect Bridge and the Aztec Network. A user would deposit funds into a bridge contract for a specific DeFi protocol. The Aztec Network's zk-rollup would then batch user intents—such as a private swap or private yield generation—and generate a succinct proof. This proof, when submitted to Ethereum, only revealed the net result of the aggregated transactions (e.g., total assets moved), not the individual user's actions or balances, effectively creating a privacy layer over existing DeFi.

A key technical feature was its use of Efficient Private Delegation. Users did not need to generate their own complex zk-SNARK proofs, which is computationally expensive. Instead, they submitted a simpler proof of intent to a network of proof relayers, who would aggregate transactions and generate the final rollup proof for a fee. This design made private DeFi interactions practical and gas-efficient for end-users, as they only paid for their share of the aggregated batch cost.

While Aztec Connect was sunset in March 2024 to make way for the full Aztec zkRollup, it served as a critical proof-of-concept for privacy-preserving interoperability. Its legacy demonstrates a working model for how confidential transactions can be integrated with the existing, transparent DeFi ecosystem without requiring protocols to rebuild their infrastructure, paving the way for more sophisticated privacy-preserving smart contract platforms.

Aztec Connect was a privacy-focused bridging protocol and zk-rollup that operated on the Ethereum mainnet from January 2022 until its official sunset in March 2024. Its core innovation was enabling private interactions with mainstream DeFi applications like Lido, Uniswap, and Curve through a system of zero-knowledge proofs (ZKPs). Users could deposit funds into the Aztec rollup, execute shielded transactions, and then batch their private interactions with external protocols via a network of bridges, all while maintaining confidentiality of their wallet balances and transaction amounts.

The protocol's architecture was built around two key components: the zk.money front-end application for users and a permissionless network of bridges operated by relayers. A bridge was a smart contract that encapsulated the logic for interacting with a specific external DeFi protocol. When a user initiated a private swap or yield action, their encrypted transaction intent was relayed to the appropriate bridge, which would then execute the public trade on the user's behalf. The resulting assets were returned to the user's private note within the Aztec rollup, with the entire flow's validity proven by a ZK-SNARK.

Aztec Connect was ultimately deprecated to make way for Aztec, the team's subsequent and more ambitious project: a fully programmable, privacy-first zk-rollup often referred to as a zk-ZK-Rollup. While Connect provided privacy for specific, pre-defined DeFi actions, the new Aztec network aims to offer general-purpose smart contract privacy. The sunsetting process involved a structured wind-down, allowing users ample time to withdraw funds from the Connect system before its contracts were permanently frozen, marking the conclusion of its successful two-year run as a pioneering privacy solution.