The cost question
What it costs to get an AI-built app production ready
There is no published market price for rescuing an AI-built app, but there is one for the person who does the work. In mid 2026 the UK median contract rate for a senior developer is £500 a day, and rate guides put senior specialists at £650 and up. The rate is not where the risk lives. Multiply any day rate by an unknown number of days and a quote can land almost anywhere. Six things decide how many days your fix takes, and you control more of them than you think.
Fixed £4,500 · 3 days · pass-or-refund · next slot w/c 3 August
What actually breaks
- The spec is a symptom, not a failure'Sign-up sometimes fails' and 'sign-up fails for any email with a plus sign in it' describe the same bug at very different prices. A precise failure statement can be estimated; a vague one means the first billed days go on turning your description into one. Before asking for quotes, write down what you did, what you expected, and what happened instead, with the exact account and time. Every hour spent sharpening the description is an hour you do not buy at contractor rates.
- No acceptance test, no finish lineThe cheapest fixes are the ones where 'done' is checkable: this flow completes, this page loads for this user, this refund appears in the ledger. 'Make it feel less flaky' has no pass or fail, so no honest engineer can bound it, and the price becomes a rate multiplied by however long you both stay patient. If you can turn your problem into a list of checks that currently fail, you have converted an open-ended engagement into a quotable job.
- One place or a pattern: the blast radiusSeverity and cost are not the same axis. A serious bug confined to one function is cheap to fix. A mild one baked into a pattern repeated across dozens of files is expensive, because the fix is dozens of edits plus checking that none of them broke a neighbour. Generated code leans toward copies rather than shared functions, so one bad decision usually lives in many places. Ask whether your problem is one place or a pattern; the answer moves the price most.
- Can anyone actually ship the fix?A fix that cannot be shipped is worth nothing, so the first billable question is whether anyone can get a change into production and confirm it landed. Where a working release pipeline exists, that part costs nothing. Where nobody can say how the last deploy happened, expect a slice of the invoice to go on establishing a repeatable route to production before the bug is even touched. That slice is legitimate work, but it surprises founders every time.
- You are paying for diagnosis, not typingIn rescue work the edit is often ten lines; finding which ten takes days. The engineer has to read code no human has read, reproduce the failure, and rule out the other plausible causes, in a codebase with no record of why anything is the way it is. An invoice that looks large next to a small diff is not padding; it is mostly diagnosis. It also means the first day is worth more than the fifth: once the cause is named, the repair is usually quick.
- Urgency meets the open meterUrgency is where day rates get expensive, because the incentives point the wrong way. On an open meter, every surprise the engineer finds extends the timeline at your cost, and you are in the worst position to negotiate: your deadline is public and your alternative is shipping nothing. A fixed price flips this; if the job runs long, the seller absorbs the overrun. Whoever carries that risk will charge for it. The choice is whether you pay a known number for certainty or an unknown one for hope.
How the price is actually arrived at
An honest fixed price is built in a specific order. First, someone reads the code and reproduces the failure, because no estimate made before that is worth anything. Second, the problem is written down as acceptance checks that currently fail. Third, the work is sized against those checks: one place or a pattern, deployable or not, how much diagnosis remains. The seller then adds a margin for what the reading did not reveal, and that margin is the price of taking the overrun risk off you. A quote produced without reading the code is not a quote, it is an opening bid. And a day rate quoted instantly is not cheaper; it is the same uncertainty, moved onto your invoice.
What “done” looks like
We agree one of these in writing before you pay anything. If it passes, the sprint passed. If it doesn't, you get a full refund and keep the work.
- The price was quoted after someone read the code, not before
- The job is written as a list of checks that fail today and must pass
- Deploy access and a route to production are agreed before work starts
- The total is fixed in writing, with overrun risk on the seller
We agree the acceptance test before any work starts. If it doesn't pass within three working days, you get a full refund and keep every change I've committed. The risk is mine, not yours.