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x401
ProtocolSpecification
Draft
An open draft protocol from Proof that lets a website or API ask an agent who it acts for and what that person approved, with signed evidence. Designed to work alongside x402 payments. Introduced in June 2026; Proof's production launch was 15 Oct 2026. Spec draft 0.2.0, Apache-2.0.
Protocol profile
- Connects
- Agent ↔ website / API (identity)
- Maturity
- Open draft · Proof
- Distinction
- Proves who an agent represents and what they authorized. Identity, not payment: pairs with x402.
- Specification
- Primary source ↗
Documented relationships · 1
Proof describes x401 as the identity step alongside x402 payments: 'x401 establishes who is behind a request… x402 enables the payment.'
Evidence ↗