Hermez Network (HEZ)

Hermez Network (HEZ): From Ethereum zk-Rollup to a Retired Polygon Asset

Hermez was an early Ethereum Layer 2 project built around zero-knowledge rollups and decentralized transaction processing. Its technology was absorbed into Polygon, while HEZ was designated for conversion into Polygon’s token. The later sunset of Polygon zkEVM Mainnet Beta makes HEZ primarily a historical and migration-related asset rather than an active network token.

What Hermez was designed to do

Hermez Network was an Ethereum Layer 2 focused initially on payments and ERC-20 transfers. Its rollup design bundled transactions away from Ethereum mainnet and used zero-knowledge proofs to verify the resulting state transition on Ethereum. Polygon’s technical account describes Hermez 1.0 as permissionless and decentralized, with a design target of up to 2,000 transactions per second. Those throughput figures are project documentation rather than an independent performance assessment.

The proposed Hermez 2.0 architecture expanded beyond transfers toward smart-contract execution. Its documented components included a zkNode, zkProver, bridge, sequencers, aggregators, and a consensus mechanism. In practical terms, transaction execution could occur off-chain, while a cryptographic proof attested to the correctness of the state changes before they were accepted by the settlement layer.

How the proving architecture worked

The Hermez 2.0 design separated transaction ordering from proof generation. Sequencers were responsible for assembling activity into batches, while provers generated evidence that the resulting computation followed the system’s rules. Aggregators could combine proofs or coordinate proving resources. The technical documentation repository covers sequencing, batching, state trees, bridges, recursive proof systems, and fee mechanics, showing that the project was a full protocol stack rather than only a token contract.

Hermez’s early network used a Proof-of-Donation model, while the later Hermez 2.0 plan described a shift toward Proof of Efficiency. The project’s own explanation says the change was intended to address auction complexity, attack exposure during bootstrapping, operating costs, and the possibility that a malicious or unreliable participant could delay service. These are design objectives and risk disclosures from the project, not evidence that every proposed property was achieved in production.

The Polygon merger changed HEZ’s role

In August 2021, Polygon announced that Hermez would join its ecosystem as Polygon Hermez. The announcement said the merger covered the technology, live solutions, team, and HEZ token. It also stated that HEZ holders would be able to exchange HEZ for MATIC at a ratio of 3.5 MATIC for each HEZ, and that MATIC would take over HEZ’s intended roles in the Polygon implementation, including security and rewards.

This means the existence of an ERC-20 contract does not establish that HEZ remains the active token of a live Hermez network. The recognized contract is still visible on Ethereum, and Etherscan retains historical metadata describing the MATIC conversion. However, Polygon’s announcement explicitly said HEZ would cease to exist after a future date, while later Polygon material described MATIC, not HEZ, as the token intended for Polygon Hermez.

The project’s current status

The original Hermez GitHub organization is no longer active, and its principal repositories are marked as archived. The archived code includes the original node, circuits, contracts, wallet interface, and documentation. That makes the repositories useful for historical and technical review, but they should not be treated as evidence of an actively maintained standalone network.

The Polygon-branded successor also did not remain a continuing production network. Polygon announced that Polygon zkEVM Mainnet Beta would be deprecated, citing development delays, difficulty supporting some upgrades, limitations affecting certain DeFi transactions, and a lack of product-market differentiation. As of July 3, 2026, Polygon states that the zkEVM Mainnet Beta sequencer has been sunset and that the network is no longer producing blocks.

What this means for users and developers

For a user researching HEZ today, the primary practical question is not how HEZ powers a current Hermez chain, but whether a particular HEZ balance was converted, remains transferable as an obsolete Ethereum token, or is subject to venue-specific restrictions. The original merger terms point to a 3.5-to-1 MATIC conversion, but the availability, status, and conditions of any conversion mechanism should be checked directly rather than inferred from the token contract or a market listing.

Developers assessing historical Hermez code should also account for the shutdown of the Polygon zkEVM deployment. Polygon says self-custodied wallet assets on the sunset network may be recoverable through its claims interface until December 31, 2027, but assets locked inside DeFi protocols, multisig contracts, or third-party bridge contracts are not covered by that interface. This distinction makes custody design and exit procedures central dependencies for any remaining application or user position.

Governance, dependencies, and limitations

Hermez’s architecture depended on more than its proof system. It required working node software, sequencers, provers, aggregators, bridge contracts, Ethereum settlement, and operational coordination. The design documentation presents permissionless participation as an objective, but the eventual availability and decentralization of each component must be assessed separately. A validity proof can constrain incorrect state transitions without guaranteeing uninterrupted service, adequate liquidity, safe bridges, or active application development.

The central editorial conclusion is therefore narrow: Hermez is historically significant as an early Ethereum zk-rollup and as the technology base for Polygon’s zkEVM effort, but HEZ should not be described as the active utility token of a live standalone Layer 2. The merger, archived repositories, and 2026 zkEVM sunset all point to a retired or legacy asset whose present status requires contract-level and custody-level verification.

Key takeaways

• Hermez began as an Ethereum zk-rollup focused on payments and ERC-20 transfers.
• Its planned architecture used sequencers, provers, aggregators, bridges, and zero-knowledge validity proofs.
• Polygon announced a merger in 2021 and specified a conversion ratio of 3.5 MATIC for each HEZ.
• The original Hermez repositories are archived, and the standalone project is no longer active.
• Polygon zkEVM Mainnet Beta, the principal successor associated with Hermez technology, was sunset on July 3, 2026.
• HEZ should be treated as a legacy Ethereum token unless its current conversion and custody status can be verified directly.

Risks and open questions

• HEZ’s live utility is unclear because Polygon’s merger announcement assigned its intended roles to MATIC and said HEZ would cease to exist.
• The existence of an Ethereum ERC-20 contract does not prove that an active Hermez network or official redemption process remains available.
• Any remaining HEZ conversion, trading, or custody route may depend on specific contracts, venues, or historical migration procedures.
• Polygon zkEVM Mainnet Beta no longer produces blocks, creating operational and withdrawal risks for assets or applications that remained on the network.
• Polygon states that assets locked in DeFi protocols, multisigs, or third-party bridge contracts are not recoverable through the zkEVM claims interface.
• Archived code and historical technical documentation cannot establish current maintenance, security support, adoption, or decentralization.