Handoff is a gasless offramp protocol that enables users to sell tokens without paying gas fees, powered by EIP-2612 and Permit2 standards.
Handoff allows users to transfer ERC-20 tokens to offramp providers without prior on-chain approvals or gas costs. Users sign permit messages off-chain, and authorized relayers submit transactions on their behalf.
User → Signs EIP-2612/Permit2 (off-chain)
→ Signs Request (off-chain)
→ Relayer → Submits to Handoff contract
→ Validates signatures
→ Executes permit
→ Transfers tokens to provider
- Gasless Transactions: Users don't pay gas fees
- Dual Permit Standards: Supports both EIP-2612 and Uniswap Permit2
- Signature-based Authorization: Off-chain permits with on-chain execution
- Replay Protection: Namespaced transaction IDs prevent cross-chain/contract replays
- Access Control: Owner-managed relayers and blacklist
- Emergency Controls: Pausable operations for security incidents
offrampWithPermit() - Executes token transfer using EIP-2612 permit
offrampWithPermit2() - Executes token transfer using Permit2
Access Control
addRelayer()/removeRelayer()- Manage authorized relayersblacklist()/unBlacklist()- Block/unblock addressespause()/unpause()- Emergency stop mechanism
Fund Management
transferNative()- Withdraw native currency (ETH/POL/etc)transferToken()- Withdraw ERC-20 tokens
constructor(
address[] memory _relayers, // Initial relayer addresses
address _permit2, // Permit2 contract address
address _owner // Contract owner (multi-sig recommended)
)- Smart contracts: Solidity
- Permit standards: EIP-2612, Permit2
- Request signing: EIP-712
- Relayer infrastructure: Openzeppelin Relayer
MIT License - Copyright (c) 2025 Cosine Labs Inc.
- Company: Cosine Labs Inc.
- Email: engineering@getcosine.app
- Website: https://getcosine.app