x428

An open standard for delegated crypto withdrawal authorization on centralized exchanges.

Named after HTTP 428 Precondition Required, the status code used for step-up 2FA.

Resource Owner
consent
Client App
OAuth 2.0 + PKCE
Exchange
on-chain tx
Blockchain

OAuth 2.0 + PKCE — no custom auth

Step-up 2FA via HTTP 428

Compliance-ready — FATF Travel Rule

GitHubWhitepaperOpenAPI Spec