Direct answer
What is the cheapest way to prove AI work to a client without building my own logging system?
Let the record write itself while the work runs. Run the job through Zambo on the free tier and the verifiable receipt exists when the work finishes, at $0, with nothing to build. Screenshots prove almost nothing, and a logging system of your own costs days. One heavy delivery day costs a $0.99 Day Pass.
By Brennan Zambo, creator of Zambo. Updated October 17, 2026.
The four methods, ranked by what they really cost
| Method | Money | Your time | What the client can actually check |
|---|---|---|---|
| Screenshots and chat exports | $0 | Minutes, then an argument | Nothing. A picture of a claim, editable by anyone, with no way to recompute it. |
| A certificate you write yourself | $0 | An evening per dispute | Your word, formatted. The client is trusting the person the proof was supposed to check. |
| Your own logging system | Days of building, then upkeep | Days, plus every future change | A record you control end to end, which is exactly why a skeptical client discounts it. |
| Receipts written by the connection | $0 on the free tier; $0.99 for a heavy day | None. The record is a byproduct of doing the work. | The receipt itself, recomputed in their browser, with no account and no trust in you required. |
The $0 route, step by step
Connect the AI you already use to Zambo (Claude, ChatGPT, Gemini, Cursor, Grok, and the other supported clients all work the same way), run the job, and send the client the handover link with the delivery. Every step of the job wrote its verifiable AER-1 receipt as it ran, the client opens the link in a browser, and the check they run is the same check you would run: the format is published as IETF Internet-Draft draft-zambo-aer1-23, so the procedure is public, not a vendor's say-so. A client who wants to spot-check a single receipt instead of the whole handover can run it at zambo.dev/verify. The cost worksheet has the full pricing picture when your days get heavier than the free tier.
Why the free methods fail the check
Cheap proof fails for one reason: the person presenting it also produced it. Screenshots, exports, and self-written certificates all ask the client to trust the presenter, which is the very thing proof exists to avoid. A receipt written by the connection while the work ran breaks that circle: you could not have edited it afterwards without breaking its check, and the client can verify that themselves. That independence is the entire value, and on the free tier it costs the same as the screenshots: nothing.
The honest part
The free tier has daily limits that vary by tool, up to 20 free calls per metered tool per day, and a big delivery day can outgrow them; that day costs $0.99, not a subscription. And the receipt proves the saved result was not changed since it was saved. It does not prove the work was good. A client can still judge the work itself; now they judge it from a record neither of you can rewrite.
Frequently asked questions
What is the cheapest way to prove AI work to a client without building my own logging system?
Run the work through Zambo on the free tier. Every call writes a verifiable AER-1 receipt as it runs, so the proof exists when the work finishes, at $0, with nothing to build and nothing to assemble afterwards. Send the client the handover link with the delivery and they check the record in a browser with no account. A heavy day that outgrows the free tier costs a $0.99 Day Pass, one time, no subscription.
Are screenshots enough proof for a client?
Screenshots are enough until the client has a reason to doubt them, which is the only moment proof matters. A screenshot can be edited in minutes and cannot be recomputed, so it settles nothing in a real disagreement. It also captures the chat, which shows what the AI said, not what its tools ran. The receipt covers the run itself: the steps, the saved results, and the times.
Why not write my own completion certificate?
Because a certificate you write about your own work asks the client to trust you, and trust is the thing under dispute. It also costs you an evening of assembling evidence from chats and files every time it is challenged. A connection-written receipt removes you from the chain: you present a record you could not have quietly edited, and the client's checker confirms that without you in the room.
What does building my own logging actually cost?
Days to build something basic, then ongoing upkeep every time your tools or workflow change, and at the end of it you own a record your client still has to take on faith, because you control the system that wrote it. The build cost is real; the trust cost never goes away. That is why the cheapest route is a record written by a connection you do not control, on a published format.
What do I send the client at the end?
One link: the handover. It gathers the job's steps, each with its verifiable receipt, the source states, and the saved results, on one page the client reads in a browser. They can check any receipt from that page and record an Accept or Flag decision on the same page. No raw chat history, no zip file of screenshots, no walkthrough call.
Your AI said "done." For $0.99, prove it: https://zambo.dev/day-pass/
The main site answers the budget version of this question head-on: the cheapest way to prove AI work to a client, without building your own logging system.
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