# Acutis Contract Buying guide: https://acutisignatius.com/agentic/contract/ Output schema: /openapi.json → paths → /v1/contracts/validate → post → responses → 200. Actual fixed response: /v1/example. Validate up to ten JSON documents against JSON Schema draft-07 or 2020-12. Returns per-document validity and actionable errors with instance paths. Runs isolated with bounded time and memory; no remote schema loading or automatic data modification. POST /v1/contracts/validate: {"schema":{"type":"object","required":["email","quantity"],"properties":{"email":{"type":"string","format":"email"},"quantity":{"type":"integer","minimum":1}},"additionalProperties":false},"documents":[{"email":"avery@example.com","quantity":3},{"email":"invalid-email","quantity":0}]} Price: 0.02 USDC (20000 atomic) on Base mainnet eip155:8453. x402 v2 PAYMENT-REQUIRED / PAYMENT-SIGNATURE / PAYMENT-RESPONSE. Validate and prepare work before payment. Result released after settlement. JSON file artifacts contain filename, MIME type, size_bytes, sha256 and base64. Decode base64 to save file bytes. Diagnostic APIs return structured JSON directly. Exact proof + normalized input delivers the cached result for 30 minutes across restarts. A proof cannot buy another input. Do not create a new authorization after ambiguous delivery. Receipt cache stores the returned result for retry delivery; central analytics omits inputs, caller identities and proofs. Empty unsigned POSTs inspect payment and Bazaar metadata without performing work. Signed empty requests return 422 before verification or settlement. Free: GET /v1/example (fixed, no customization), /docs, /openapi.json, /service.json, /health. Production has no free custom-work bypass. One-megabyte JSON request limit. Bounded instance concurrency; 429 Retry-After when busy. Bazaar discovery metadata is declared; external directory listing is not guaranteed.