Settlement
Permit2
Permit2 is a Uniswap contract for signature-based approvals and transfers of ERC-20 tokens. A holder can permit a spender, or sign a transfer, without a separate onchain approve transaction. The x402 version 2 spec names permit2 as an EVM asset transfer method alongside EIP-3009.
Explanation
EIP-3009 only works for tokens that implement that function. USDC does. Many other ERC-20 tokens do not. Permit2 is a shared contract those tokens can flow through: the user grants Permit2 an allowance, then signs transfers that a facilitator can execute. Uniswap's documentation describes the allowance and signature-transfer model.
For measurement, permit2 and eip3009 are ways to authorize the same kind of settlement. This index does not split volume by which signature standard the facilitator used, because the Transfer log does not say. A Permit2 payment that settles as USDC from a registered facilitator is x402 volume. The signature standard is not a second protocol.
Live data
Related terms
Sources
- Permit2 overview — Uniswap
- x402 Protocol Specification, version 2 — Coinbase x402
- EIP-3009: Transfer With Authorization — Ethereum Improvement Proposals