zkPorter

zkPorter is a data availability scaling solution for zkRollups, specifically developed by Matter Labs for the zkSync ecosystem. It functions as a hybrid model where users can choose between two types of accounts: zkRollup accounts, which post data to Ethereum for maximum security, and zkPorter accounts, which post data to a separate, off-chain network of Guardians. This separation allows zkPorter to offer transaction fees that are 1/100th of Layer 1 costs while maintaining security through cryptographic proofs and a decentralized staking mechanism.

The core innovation of zkPorter is its off-chain data availability committee (DAC) model, secured by zkSync token (ZK) stakers known as Guardians. These Guardians stake tokens to attest to the availability of transaction data off-chain. The system's security is enforced because if data is withheld, the zkSync Era sequencer cannot produce a valid zero-knowledge proof (ZK-proof) for the state transition, and the staked assets of malicious Guardians can be slashed. This creates a strong cryptoeconomic guarantee that data remains available for verification.

Compared to a pure zkRollup, which inherits Ethereum's full security by posting all data as calldata on-chain, zkPorter makes a distinct trade-off. It sacrifices the Ethereum-level data availability guarantee for drastically lower costs and higher throughput. This makes it ideal for applications like high-frequency trading, gaming, and social media where ultra-low fees are critical. Users consciously select their security model based on the needs of their assets and activities.

zkPorter's architecture is a direct response to the high cost of on-chain data storage. By moving data availability off-chain but securing it with staked economic incentives and the underlying validity proofs of the zkRollup, it provides a pragmatic path to mass adoption. It is a key component of zkSync's vision for a multi-layered network, offering users a spectrum of security and cost options rather than a one-size-fits-all scaling approach.

At its core, zkPorter introduces a novel data availability (DA) model. Unlike a pure zk-rollup, which posts all transaction data to the Ethereum L1, zkPorter allows users to choose between two account types: zkSync Era (secured by Ethereum) and zkPorter (secured by zkSync Guardians). Transactions in zkPorter accounts have their validity proofs verified on-chain, but the transaction data itself is stored off-chain by a decentralized network of Guardians, drastically reducing gas fees. This hybrid approach is often categorized as a validium.

The security of funds in zkPorter accounts is enforced by the zkSync Guardians, a proof-of-stake (PoS) network separate from Ethereum. Guardians stake the native ZK token and are responsible for signing off on the availability of data for zkPorter blocks. If a Guardian acts maliciously by withholding data, their stake can be slashed. This creates a strong cryptographic and economic guarantee that the data necessary to reconstruct user balances will remain accessible, preventing theft of funds.

From a user's perspective, interacting with zkPorter is seamless. Wallets and dApps can support both zkSync Era and zkPorter accounts, allowing users to select their preferred trade-off between cost and security for each transaction. High-value transfers might use the L1-secured rollup mode, while high-frequency, low-value actions like gaming or social transactions can leverage the ultra-low fees of zkPorter. This flexibility is key to achieving mass adoption for everyday blockchain use cases.

The technical mechanism relies on zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge). All transactions, whether in zkSync Era or zkPorter mode, are batched together. A single validity proof for the entire batch is generated and posted to Ethereum L1, proving the correctness of all state transitions. The critical difference is where the underlying data for the zkPorter portion resides, enabling the system to inherit Ethereum's security for proof verification while outsourcing costly data storage.

zkPorter is a hybrid Layer 2 scaling architecture, pioneered by zkSync, that splits the network into two distinct data availability modes: a zk-rollup chain with data published on Ethereum and a zkPorter chain with data secured by a decentralized network of Guardians. This design allows users to choose between the highest security of Ethereum's base layer and the ultra-low transaction fees of an off-chain data availability solution. The core innovation is that both modes share the same unified state and are secured by the same zero-knowledge proofs, enabling seamless interoperability.

The security of the zkPorter chain is underpinned by its Guardians, a decentralized set of token holders who stake the network's native token (e.g., ZK) to participate. Guardians are responsible for monitoring and signing off on the availability of data for the zkPorter chain. Their role is purely economic: they must cryptographically attest that the data is available and can be challenged via a data availability challenge. If a Guardian acts maliciously or fails to perform their duty, their staked tokens can be slashed, creating a strong financial disincentive for bad behavior.

This security model is often described as an economic security guarantee, contrasting with the cryptographic security guarantee provided by publishing data directly to Ethereum. While validators in the zk-rollup side must only generate valid proofs, Guardians for zkPorter have the additional responsibility of ensuring data is published and stored. This creates a trade-off: transactions on the zkPorter side benefit from drastically reduced fees because data is not posted to Ethereum, but they accept a security model based on cryptoeconomic incentives rather than pure Layer 1 finality.

The practical implication is a flexible ecosystem. High-value transactions, such as large DeFi operations, can opt for the zk-rollup mode for maximal security. Meanwhile, high-frequency, low-value activities like payments, gaming, and social interactions can leverage the zkPorter mode for near-zero fees. Because the state is unified, assets can move freely between the two security modes without cumbersome bridging, allowing users and applications to dynamically choose the optimal security-cost profile for each transaction.