zkSync Era

zkSync Era's zkEVM is a virtual machine that executes Ethereum smart contracts and generates zero-knowledge proofs (ZKPs) of the computation. This allows it to be EVM-compatible, meaning developers can deploy existing Solidity/Vyper code with minimal changes, while still leveraging the scaling benefits of ZK-rollup technology.

As a ZK-Rollup, zkSync Era bundles thousands of transactions off-chain, generates a cryptographic proof (a ZK-SNARK), and posts a single proof to the Ethereum mainnet for verification. This architecture is key to its properties:

• Security: Inherits Ethereum's security via cryptographic validity proofs.
• Scalability: Reduces on-chain data and computation by orders of magnitude.
• Finality: Offers near-instant finality after proof verification on L1.

zkSync Era has native account abstraction at the protocol level, meaning every account is a smart contract wallet. This enables powerful user experience features by default, such as:

• Sponsored transactions (gasless meta-transactions).
• Batch transactions (multiple ops in one signature).
• Custom security logic (social recovery, multisig).
• Paymaster support for paying fees in ERC-20 tokens.

The ZK Stack is a modular, open-source framework for building custom ZK-powered L2s and L3s (Hyperchains). Developers can launch sovereign chains with:

• Shared security via Ethereum settlement.
• Customizable virtual machines (zkEVM, zkVM).
• Own data availability modes.
• Interoperability via native cross-chain communication. This creates an ecosystem of interconnected, scalable chains.

Boojum is zkSync Era's in-house, STARK-based proof system written in Rust. It replaces older SNARK systems to provide:

• Faster proof generation without trusted setups.
• Reduced hardware requirements, enabling proof generation on consumer-grade GPUs.
• Enhanced decentralization by lowering the barrier to becoming a prover.

To minimize L1 gas costs, zkSync Era uses advanced data compression for transaction calldata. Key techniques include:

• Storage diffs: Only storing the difference in state before/after a transaction batch.
• Efficient encoding: Using specialized formats like EIP-712 for signatures and optimized ABI encoding.
• L1→L2 communication: A secure messaging bridge that compresses arbitrary data for efficient cross-chain calls.

zkSync Era has native account abstraction (AA) built into its protocol at the VM level. This enables features like:

• Paymasters: Allow third parties to sponsor transaction fees for users.
• Signature abstraction: Support for any cryptographic signature scheme (e.g., ECDSA, EdDSA).
• Smart contract wallets: Every account is a smart contract, enabling programmable transaction logic and social recovery. This core design removes the distinction between Externally Owned Accounts (EOAs) and contracts.

The zkSync Era Virtual Machine (zkEVM) is a custom, register-based VM that executes EVM-compatible bytecode. Key aspects include:

• LLVM-based compiler: Translates Solidity/Vyper into custom zkEVM bytecode for efficient proof generation.
• EVM equivalence: Aims for high compatibility with Ethereum tooling and contracts, though with some differences in opcode support and gas metering.
• ZK-circuits: The execution is verified by zero-knowledge proofs (ZK-SNARKs) that are posted to Ethereum L1.

The ZK Stack is an open-source framework for building custom ZK-powered L2s and L3s, called Hyperchains. This ecosystem model enables:

• Sovereignty: Teams can deploy their own chains with customizable logic, data availability, and sequencers.
• Interoperability: Hyperchains are natively connected via the ZK Stack's cross-chain messaging protocol.
• Shared security: All Hyperchains inherit security from Ethereum via validity proofs, creating a unified Hyperbridge network.

Boojum is zkSync Era's high-performance, open-source STARK-based proof system. It represents a major upgrade from previous SNARK-based systems, offering:

• Faster proof generation: Designed for efficiency on consumer-grade hardware.
• Transparent setup: Eliminates the need for a trusted ceremony, enhancing decentralization.
• Recursive proof aggregation: Multiple proofs can be aggregated into a single proof for efficient L1 verification, reducing finality costs.

zkSync Era provides a suite of tools and supports emerging standards for developer adoption:

• zkSync Hardhat Plugins: For local development, testing, and deployment.
• Custom Gas Token: Fees can be paid in any ERC-20 token via the paymaster system.
• New Standards: Implements ERC-4337 for account abstraction and explores ERC-7121 for efficient smart account creation.
• Portal Bridge: The official bridge for transferring assets between Ethereum L1 and zkSync Era L2.

The zkSync Era ecosystem hosts a wide range of decentralized applications, including:

• DeFi Protocols: Major DEXs (e.g., SyncSwap, Maverick), lending markets, and derivatives.
• NFT Marketplaces & Gaming: Platforms leveraging low fees for digital assets and on-chain game logic.
• Infrastructure: Wallets (e.g., Argent), oracles, and indexers built with native AA support.
• Governance: Managed by the zkSync Token Assembly and eventually a decentralized ZKsync Governance system.

A Layer 2 scaling solution that bundles (rolls up) hundreds of transactions off-chain, generates a cryptographic proof of their validity, and posts this single proof to the base layer (Ethereum). This is the core architecture that zkSync Era implements, enabling high throughput and low fees while inheriting Ethereum's security.

• Validity Proofs: Uses zero-knowledge proofs (specifically zk-SNARKs) to prove state transitions are correct.
• Data Availability: Transaction data is published on Ethereum as calldata, ensuring anyone can reconstruct the state.

A virtual machine compatible with the Ethereum Virtual Machine (EVM) that can produce zero-knowledge proofs for the execution of smart contracts. zkSync Era's zkEVM allows developers to deploy existing Solidity/Vyper contracts with minimal changes.

• Bytecode-Level Compatibility: Interprets standard EVM opcodes, not just high-level language.
• Proving Overhead: The major technical challenge is generating proofs for arbitrary EVM computation efficiently.

Zero-Knowledge Succinct Non-Interactive Argument of Knowledge. This is the specific type of cryptographic proof system used by zkSync Era (v24 and later).

• Succinct: Proofs are small and fast to verify.
• Non-Interactive: The prover generates a proof without needing back-and-forth with the verifier.
• Trusted Setup: Earlier versions required a trusted setup ceremony (e.g., Powers of Tau), though modern implementations like Boojum aim to be trustless.

zkSync Era's high-performance, STARK-based proving system. It represents a major upgrade from the previous SNARK-based prover.

• STARKs: Uses transparent, post-quantum secure proof systems, eliminating the need for a trusted setup.
• Performance: Designed for extreme efficiency, making proof generation faster and more cost-effective.
• Unified Circuit: Processes all transaction types (e.g., swaps, transfers) in a single proof for optimal throughput.

A core feature where every account in zkSync Era is a smart contract wallet by default, unlike Ethereum's externally owned account (EOA) model. This enables:

• Sponsored Transactions: Protocols can pay gas for users.
• Batch Transactions: Multiple operations in a single signed transaction.
• Custom Security Logic: Social recovery, multisig, and session keys built directly into the account protocol.