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Always verify contract addresses from official sources before interacting with them

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Contract Suite

Biconomy is versioning our smart contracts by groups. One “Suite” version contains many different versioned contracts within itself. The contracts being versioned are:
  • Nexus Account
  • Modular Execution Environment (MEE) K1 Validator (ERC-7579 Module)
  • Nexus Boostrap & Factory
  • Composability & Fusion Utils (Composable Storage, ETH Forwarder)

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Versions

Use 2.2.3 (Nexus 1.3.3) for all new accounts. Nexus versions before 1.3.3 have a re-initialization issue, fixed in 1.3.3 by making account initialization single-use per transaction. The earlier suites below are listed only to derive the address of accounts already created on them. Do not deploy new accounts with them.Version numbers do not indicate which suite to use: 2.3.0 is numbered above 2.2.3 but is an unaudited release candidate built on Nexus 1.3.1.
What’s New:
  • Nexus 1.3.3. Account initialization is single-use per transaction
  • Bundles the audited ERC-8211 Smart Batching reference implementation (Ethereum Foundation & Biconomy)
  • Reviewed by Pashov Audit Group (July 2026)
This is the version to use for newly created accounts. See Account Migration for what this means for accounts you already have.

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Nexus & MEE

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ERC-8211

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Utility

Only the Nexus implementation and the account factory change in this release. The bootstrap, validator, ERC-8211 and utility contracts are byte-identical to v2.2.2 and keep their existing addresses.
What’s New:
  • New fusion mode safe-sa which allows using Safe accounts as master accounts instead of EOAs
Attention! This version utilizes unaudited cotracts. It is built on Nexus 1.3.1, not 1.3.3, and is not intended for production accounts.

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Nexus & MEE Validator

Superseded by v2.2.3. Nexus 1.3.2 has the re-initialization issue fixed in 1.3.3. Do not use for new accounts; these addresses are listed only for deriving addresses of accounts already created on this version.
What’s New:
  • Bundles the audited ERC-8211 Smart Batching reference implementation (Ethereum Foundation & Biconomy) — the formal standardization of the composability primitives shipped in earlier versions
  • Expanded composability primitives and pipeline hardening
  • Audited by Pashov (May 2026)

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Nexus & MEE

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ERC-8211

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Utility

Superseded by v2.2.3. Nexus 1.3.1 has the re-initialization issue fixed in 1.3.3. Do not use for new accounts; these addresses are listed only for deriving addresses of accounts already created on this version.
What’s New:
  • New composability version - enables native token runtime injection
  • Sign EIP-712 Data Struct instead of blind Stx hash for the smart-account mode
  • New ERC-7702 Nexus accounts can be initialized via relayers
  • Gas optimizations

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Nexus & MEE Validator

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Composability & Utility

What’s New: K1 MEE module introduced - enables ERC-7702-delegated EOAs to own Nexus accounts

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Nexus & MEE Validator

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Composability & Utility

Major release with Nexus 1.2.0, ERC-7702 support, and native composability

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Nexus & MEE

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Composability & Utility

Compiled for EVM Paris (No PUSH0, no MCOPY, no TSTORE)

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Nexus & MEE

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Composability & Utility

Added Nexus Account Factory at 0x000000903887EA36EBe051038287f49fD4A07733
Initial release - Requires manual installation of MEE K1 validator and Composability module
GitHub Release →

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Nexus & MEE

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Composability & Utility

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Nexus Audits

Cyfrin

Competition Audit

Spearbit

Zenith

Full Review

Pashov

2025 Review

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MEE Stack Audits

MEE Stack

Audited by Zenith
  • MEE EntryPoint
  • Node Paymaster
  • MEEK1 Validator

Composability Stack

Multiple Auditors

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Legacy Contracts

These contracts are deprecated. Use the latest version for new deployments.

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Base & Optimism

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Other Chains