Direct answer
Check AI Work for Free
You can check AI work for free, right now, with no signup. Open any Zambo receipt at zambo.dev/verify and the verifier recomputes the fingerprint over the saved result in seconds and shows whether the record has changed since it was saved. Running work is free to start too: free calls every day on the tools, and a free live demo that hands you a real receipt to check. This page shows the free checks for agent task completion, AI code changes, AI output, and AI research, and states exactly where free ends.
Updated October 20, 2026.
What free honestly covers here
Free has to mean something specific or it means nothing, so here is the split. Checking is free: verifying a receipt at zambo.dev/verify costs nothing, needs no account, and is not metered in any way that matters, because a check is a recomputation anyone should be able to run. Trying is free: the live demo at zambo.dev/demo runs a real call and returns a real receipt, and the tools on the Zambo MCP include free calls every day, enough to run real checks on real work before spending anything. Producing records at volume is the paid part, and the price is stated on this page rather than discovered later: a Day Pass is $0.99 for 24 hours of full access, and the Zambo Pass is $29 a month for ongoing use.
That split is deliberate. Proof only works if the checker pays nothing and asks no one's permission. The moment verification needs a subscription, the checked party controls the evidence again, and the whole exercise collapses back into trust.
How to check a receipt for free, in under a minute
The check is five questions, in order. One: does a receipt exist for the step being claimed? Two: does it name the tool and the run the claim is about? Three: does its fingerprint recompute over the saved result, which is the test that catches any later edit? Four: do its fields agree with the claim, the right input, the right output, the right time? Five: is its place in the job's chain intact, so the steps add up to the whole job? The verifier at zambo.dev/verify walks these for you when you open a receipt link. Steps that pass are proven as recorded. Steps with no receipt are unchecked, and the honest response to an unchecked step is to redo it, reprice it, or disclose it, not to argue about it.
Free check: agent task completion
An agent says the task is complete. The free check is to ask for the receipts behind the claimed steps and open them. Each receipt shows the tool that ran and the result it saved, in order, so completion stops being a verdict the agent issues about itself and becomes a chain you can walk. This is the check that matters most for overnight and delegated runs, where nobody watched the work happen. If the chain covers the task, the completion claim stands on records. If the chain stops halfway, you have learned something a status message would never have told you, for free.
Free check: AI code changes
Before you merge, ship, or pay for AI-written code, check the receipts behind the change: the files read, the edits made, the tests run and what they returned. Checking each receipt is free at zambo.dev/verify, and the chain shows the work in the order it happened, including the failed test runs that were fixed along the way, which is usually where the truth of a change lives. Pair it with your normal review of the diff. The diff shows what is different; the receipts show how it got that way.
Free check: AI output and AI research
For a report, a summary, or a researched claim, the free check is to open the receipts of the calls behind it: the sources fetched, the prices checked live, the audits run. Each receipt fixes the result as it stood when the call ran, so you check the claim against the saved result, not against a live page that may have changed since. This is how you check AI research without redoing it: the trail either supports the sentence or it does not, and either answer costs you a minute.
Free checks for freelancers
Freelancers get asked to check work in both directions: their own AI's output before it ships, and the record when a client questions it afterward. Both checks are free. Run the end-of-job verification calls while you still have free calls in the day, attach the receipt links or one handover link from zambo.dev/handover to the deliverable, and the client's check is free on their side too. When a payment argument starts, the receipts end the factual part of it: the steps either ran and saved those results, or they did not.
Where free ends, and what a full day costs
Free ends at volume, and at work that was never recorded. A full day of client work, a long agent run, or a team producing records all day runs past the free daily calls; a Day Pass covers that day for $0.99, one payment for 24 hours, and the Zambo Pass covers ongoing use at $29 a month or $290 a year, $19 a month for $ZAMBO holders, with full pricing at zambo.dev/pricing. And no tier can check a record that does not exist: a chat answer produced with no tool calls carries no receipt, whichever plan you are on. The fix for that is to run the work through the tools, which is the whole design: connect Zambo at zambo.dev/mcp to the AI you already use, and the records make themselves.
Honest limits
A free check proves the saved result was not changed after the fact. It does not prove the result was correct, the sources were good, or the work was worth the invoice; judgment still applies. Free calls reset daily and vary by tool, and the exact allowance is stated on the tool, not hidden. AER-1, the receipt format underneath Zambo, is an IETF Internet-Draft (draft-zambo-aer1-24), not a finalized standard.
Frequently asked questions
Is there a free way to check AI work?
Yes. Checking a receipt is free at https://zambo.dev/verify/ with no signup and no account: open the receipt link, and the verifier recomputes the fingerprint over the saved result and shows whether the record has changed since it was saved. Running work is free to start as well: Zambo tools include free calls every day, and the live demo at https://zambo.dev/demo/ runs a real call and hands you a real receipt to check. What is not free forever is volume: past the daily free calls, a Day Pass is $0.99 for 24 hours.
How do I check a receipt for free?
Open the receipt link, or paste its id at https://zambo.dev/verify/. The verifier runs five checks: a receipt exists for the step, it names the right tool and run, its fingerprint recomputes over the saved result, its fields agree with the claim being made, and its place in the job's chain is intact. The whole check takes seconds, in a browser, and the person who did the work does not need to be involved, online, or cooperative. If a step has no receipt, that is the answer for that step: it is unchecked.
Can I check AI code changes for free?
Yes. If the coding work ran through the Zambo MCP, every call left a receipt: the reads, the edits, the test runs, with the saved result of each. Checking any of those receipts at https://zambo.dev/verify/ is free, and walking the chain in order shows you the work behind a change before you merge it, pay for it, or ship it. Code that was changed outside the MCP has no receipt to check, and no tool can check a record that was never made; the free check tells you that too, by absence.
What does the free tier not cover?
Stated plainly: verification is free without practical limit, because checking a receipt costs the checker nothing but seconds. Producing records is where the meter runs. Free calls every day cover real testing and small jobs; a full day of client work, an overnight agent run, or a whole team's output runs past them. A Day Pass at $0.99 covers 24 hours of full access, and the Zambo Pass covers ongoing use at $29 a month. Free also cannot check work that was never recorded: a chat answer with no tool calls behind it has no receipt.
How do freelancers check AI work for free?
The same way anyone does, pointed at the jobs freelancers actually argue about. Before you send a deliverable, run the final checks through Zambo so the work carries receipts your client can verify free at https://zambo.dev/verify/. When a client questions an invoice, send the receipt links or one handover link instead of a defense: the record shows the steps and the saved results, and the client checks them without an account. Free daily calls cover the end-of-job checks on most solo projects; the Day Pass covers a full delivery day for $0.99.