What is a Zambo receipt?
A Zambo receipt is the verifiable record of one step of AI work. When a step runs through the Zambo connection, the receipt commits to the caller, the tool, the output, any side effects, and the format version, at the moment the result is saved. Anyone can recompute it later to check the saved result was not changed.
The name is the plain-language brand for the technical object: an AER-1 receipt (AER-1, IETF Internet-draft-zambo-aer1-21). People say "get me a Zambo receipt" the way they would ask for a receipt for anything else of value: the small, checkable proof that the thing happened as recorded.
What a receipt proves is deliberately narrow, and the narrowness is the trust mechanism. It proves the saved result it commits to was not changed since it was saved. It does not prove the work was good, that the answer was right, or that anything happened outside the recorded step. Claims beyond the record are argued from the work and its sources, whose states the surrounding job record shows.
Receipts compose: a job is a chain of step receipts, presented to a client as a handover, with the client's decision recorded on the same object. The check is public: take any receipt ID to https://zambo.dev/verify/ and recompute it yourself. That public checkability, by strangers, without an account, is the property that separates a receipt from a log line or a screenshot.
Reference: the receipt in one view
Committed fields: caller (who or what ran the step), tool (what ran), output (the saved result), side_effects (what else the step changed), receipt_schema_version (the AER-1 format version). Shown around it on the job record: the step's time, its producer label, and the source states behind it. Proves: the saved result was not changed since saving. Does not prove: correctness, quality, or anything outside the step. Check: any receipt ID at https://zambo.dev/verify/ , or with the open kit, offline.
Worked example
A real receipt chain is readable on any public handover: https://zambo.dev/handover/45434a17-4afc-486a-9646-e689bcee4297 shows a job whose steps each carry their receipts, under a recorded client acceptance. Pick any step and run its ID through the verify page: the recompute either matches or it does not, and no account or permission is involved.
Frequently asked questions
Is a Zambo receipt the same as an AER-1 receipt?
Yes. Zambo receipt is the everyday name; AER-1 is the open format the receipt follows, published as an IETF Internet-Draft so other tools can mint and check the same receipts.
Do I need Zambo to check a receipt?
No. The public verify page is the easy path, and the open AER-1 kit lets anyone verify independently. A receipt that only its issuer can check would be a claim, not a receipt.
What does it cost to get one?
Receipts come from work run through the connection: the free tier covers first jobs every day, the Day Pass at $0.99 covers a full proof day, and the Pass at $29 a month covers the habit. The receipt itself is part of the work's record, not a separate product.
By Brennan Zambo, founder of Zambo.
Last verified: 2026-10-17.
Try a handover
A handover gives your client one proof link with verifiable receipts to review, then Accept or Flag.
try it: say 'use zambo to hand this over to <client>' in your ai