A2A Agent Card Validator & Extension Checker

An A2A Agent Card published at /.well-known/agent-card.json is how one agent discovers another's identity, skills, and capabilities — and it's the layer AP2 rides on. This tool validates the card against the A2A v1.0 shape, checks the signed-card signatures block, and confirms an AP2 / x402 extension is declared correctly.

⚠ A2A reached v1.0 in early 2026 (Linux Foundation). Field names reflect v1.0; verify against the A2A schema. This tool checks structure only — it does not cryptographically verify a signed card.

A2A v1.0 Signed Agent Card Zero PII Client-Side · No Network

Scope & reliance — 🔒 All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only. Structure/shape checks only — no card is fetched and no signature is cryptographically verified. Deterministic · zero PII · CC BY 4.0.

▸ Validate an agent-card.json

Paste the agent card served at /.well-known/agent-card.json. An example is pre-loaded; the second button loads a signed card.