Anchor an AI agent decision or audit record to Base mainnet
Anchor an AI agent decision or audit record to Base mainnet. Submit {schema, payload_hash (SHA-256 hex, 64 chars), metadata}; service queues into a Merkle batch and returns a receipt with pending_anchor status immediately. Full Merkle proof and on-chain anchor_tx available via free GET /v1/notarize/:receipt_id after batch anchors (within batch_threshold receipts or 120s). Include Idempotency-Key header to prevent double-charges on retry.
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://x402.fairseal.io/v1/notarize
| Category | Code and developer |
|---|---|
| Provider host | x402.fairseal.io |
| Networks | eip155:8453 |
| Payment schemes | batch-settlement, exact |
| Self-reported calls, 30 days | 3 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
We never call tools that send, buy, move money or file anything, not even without paying.
Example input (from the provider)
{
"body": {
"metadata": {
"agent_id": "my-agent-v1",
"decided_at": "2026-09-12T10:00:00Z",
"decision_hash": "b94f6f125c79e3a5ffaa826f584c10d52ada669e6762051b826b55776d05a3d7",
"input_hash": "a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3"
},
"payload_hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
"schema": "agent_decision"
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"properties": {
"metadata": {
"description": "Schema-specific metadata. agent_decision requires {agent_id, decided_at, input_hash, decision_hash}",
"type": "object"
},
"payload_hash": {
"description": "SHA-256 hex of full payload (64 lowercase hex chars)",
"pattern": "^[0-9a-f]{64}$",
"type": "string"
},
"schema": {
"enum": [
"agent_decision",
"audit_evidence",
"probe_record"
],
"type": "string"
}
},
"required": [
"schema",
"payload_hash",
"metadata"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}