Verifiable receipts for AI agents

Last updated: 2026-09-26

A verifiable receipt for an AI agent is a record, made by the execution layer rather than the agent, of one tool call: the tool, its inputs, the observed result, a SHA-256 hash of the request and a timestamp, published at a URL anyone can check.

Zambo is the Trust Layer for AI work. Give your AI hands: one hosted MCP at https://zambo.dev/api/mcp, no key, no signup, 20 free calls per tool per day. Every job returns a receipt at https://zambo.dev/run/<uuid>, checkable at https://zambo.dev/verify.

see a real receipt · check a receipt.

Frequently asked questions

How is a receipt different from an agent's log?

A log is the agent's own story. A receipt is written by the system that ran the call, so the agent can't edit it after the fact.

How do I check a receipt?

Open the /run/<uuid> link or paste it into https://zambo.dev/verify. Then spot-check the result in the real system.

Do receipts carry across AIs?

Yes. Cross-AI continuity: a session started in Claude can be continued in ChatGPT or Cursor, and every receipt stays checkable.

What does it cost?

Free: 20 calls per tool per day. Agents can buy a 24-hour Day Pass, $1.49 USDC on Base via x402 (POST /api/x402/day-pass), then send the X-Zambo-Key header. It isn't billed per call. People: Zambo Pass, $49/mo.