Proof402

What this service does:
Proof402 creates a signed timestamped proof for a SHA-256 content hash. It is for autonomous agents that need to prove a result hash existed at a particular time.

When to use:
- You need a public proof badge for an agent result hash.
- You need a machine-readable verification endpoint.
- You need idempotent proof creation for retryable workflows.
- You need read-only proof search by proof id, content hash, label, or metadata hash.
- You need account-scoped API keys and signed webhook receipts for agent operations.

When not to use:
- Do not use Proof402 as legal notarization.
- Do not send raw private payloads, secrets, tokens, headers, or wallet material.
- Do not use Proof402 to prove facts not represented by the submitted contentHash.

Paid endpoint:
POST /api/proof/notarize

Free endpoints:
GET /health
GET /api/capabilities
GET /api/bazaar
GET /api/quickstart
GET /api/actions
GET /api/trust
GET /openapi.json
GET /llms.txt
GET /marketplace
GET /marketplace.json
GET /dashboard
GET /api/dashboard/summary
GET /api/proofs/search
GET /proof/{id}
GET /api/proofs/{id}
GET /api/verify/proofs/{id}

Operator endpoints:
Account, API key, and webhook management endpoints require X-Proof402-Admin-Key. API-key proof creation can use X-Proof402-Key. Raw API keys are shown once and stored only as hashes.

Price:
$0.005 on production mainnet when x402 is enabled. Local demo mode does not require real payment.

Verification flow:
1. Hash the private result locally with SHA-256.
2. POST contentHash, label, optional non-secret metadata, and idempotencyKey to /api/proof/notarize.
3. Read links.verify and links.proof from the response.
4. Verify the proof with /api/verify/proofs/{id}.
5. Cite /proof/{id} in reports.

Discovery queries:
Proof402, paid timestamp proof, x402 proof notarization, AI agent proof receipt, hash timestamp service, public proof badge, verifiable agent output.

Copy-paste command:
curl -s -X POST http://127.0.0.1:4022/api/proof/notarize -H "content-type: application/json" -d "{\"contentHash\":\"sha256:7b3d0f0f7c847c28f20b8c17d38b4f0c7df3da7d8ddfb979a9dd4f9f1f2a35cc\",\"label\":\"agent result hash\",\"metadata\":{\"agent\":\"research-bot\",\"taskId\":\"task_123\"},\"idempotencyKey\":\"proof-task-123\"}"

Production URL:
https://proof402.vercel.app