AI App Builder Audits · AI Development Series
a0.dev App Audit
a0.dev can take you from a description to a listed app remarkably quickly. That compresses the point at which anyone would normally have checked what is in it.
What a0.dev actually hands you
a0.dev generates complete React Native applications from a description and carries them all the way through to store submission in one flow. The code is genuine, standard React Native rather than a proprietary abstraction.
What a a0.dev application is made of
- Framework React Native, via Expo
- Language JavaScript or TypeScript
- Platforms iOS and Android
- Backend Whatever you connect it to
- Distribution Build and submit to both stores from the platform
- Export Real project code you can take elsewhere
The distinguishing feature is how little sits between an idea and a published app. That is genuinely impressive and it is also the risk: the steps that a normal release process would force — someone reading the code, someone asking what data this collects, someone checking what keys are in the bundle — are the steps that got removed.
Everything true of any React Native app applies here. The bundle ships to the user's device and can be unpacked and read. Nothing inside it is secret.
What we consistently find
The pattern in fast-generated mobile apps is consistent.
Credentials shipped to every device
Keys embedded in the app to make it work during the build stay embedded when it goes to the store. Anyone can extract them from the downloadable package.
Third-party service keys are the usual casualties, and the first sign is normally an unexpected bill or a rate limit you did not cause.
What it costs you: permanently leaked credentials that must be rotated, not patched.A backend that believes the app
Where a backend has been generated alongside, it commonly trusts what the app sends: prices, quantities, user identifiers, permission levels. The app is not a trustworthy source, because it belongs to the user.
Any check that exists only in the app is a check that does not exist.
What it costs you: users able to submit whatever values they choose.Store obligations nobody has met
Both stores require a privacy policy and an accurate declaration of what data your app collects, and both will reject or remove apps that get this wrong. Generated apps frequently collect more than the founder realises — analytics, device identifiers, crash data.
This is not a security finding so much as a commercial one, but it is the sort of thing that stalls a launch or pulls a live app down.
What it costs you: rejection, delisting, or a compliance problem discovered late.Where a0.dev is genuinely good
Getting a real, native app into both stores is normally a slow and irritating process, and a0.dev genuinely compresses it. For proving whether an idea deserves a mobile app at all, that speed is worth a lot.
Genuinely well suited to
- Testing whether an idea needs a mobile app
- Getting something installable in front of real users fast
- Internal apps for a small, trusted group
- Prototypes intended to be rebuilt properly if they work
- Founders who need to demonstrate something concrete
Where it needs engineering behind it
- Apps handling personal data, health data or payments
- Anything where tampering with the app would benefit a user
- Multiple customers whose data must never mix
- Anything facing a client security review
- Apps you intend to maintain across years of OS updates
The honest summary: a0.dev removes the friction between an idea and a live app, and the friction it removes includes the parts where somebody would normally have checked. That is fine for a prototype and a problem once it is on real phones.
Prefer to watch? The short version of who we are and how we work
Do you need an audit?
Get it looked at if
- The app is live in the App Store or Google Play
- It stores personal data of any kind
- It takes payments or sits near anything that does
- You are not certain what data it collects
- A client or partner has asked about your security
You are probably fine if
- It is only installed on your own device
- It holds nothing you would mind losing or leaking
- It is a prototype shared with a handful of testers
- It talks to nothing and stores nothing
Questions about auditing a a0.dev build
Not by default. The two faults we see repeatedly are credentials shipped to every device that installs the app, and a backend that trusts whatever the app tells it. Either one on its own is enough to expose data.
The stack it produces, React Native and Expo, is used by serious apps everywhere. The specific risk is how quickly a0.dev takes you from idea to the app stores. Publishing is easy enough that it can happen before anyone has checked what is being published.
Yes, and it does not take a specialist. An installed app can be unpacked and its bundle read. Any key inside it is effectively published, so the protection has to sit on the server, where it decides what that key is actually allowed to do.
If the backend accepts the app's word for who is asking, then yes. Requests can be modified before they are sent. The server has to establish identity itself from the session rather than reading it out of the request.
Once the backend verifies identity independently and you have checked what the app stores locally. If you have published to the app stores you have also made declarations about data handling, and those declarations need to be true.
Both stores require an accurate privacy declaration covering what you collect and share, and account deletion where accounts exist. Generated apps rarely arrive with either handled. It is usually straightforward to put right, but it is not optional and it does get checked.
Server-side fixes are the cheaper half and the more urgent. Store compliance is usually small. The audit is £495 + VAT, delivered in five working days, and tells you what needs doing in what order. Credited back in full if we do the work.
Most findings can be fixed and released as an update, and Expo lets JavaScript changes reach users without a full store review. Leaked credentials are the exception and need rotating immediately rather than patching. If we find something that urgent we tell you the day we see it rather than waiting for the report.
Less urgently, but the bundle is still distributed and still readable, so embedded keys are still exposed. If it only talks to systems your staff could reach anyway, the risk is modest. If it holds customer data, being internal does not help.
No, and we would rather say so plainly than pretend otherwise. We build with Claude Code and Cursor, with senior developers designing the system, reviewing every change and testing it. What makes us useful here is not a0.dev expertise, it is that it produces React Native and Expo, which is ordinary mobile engineering.
Built with something else?
We audit what these tools produce, whichever one you used.
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The audit
Find out what you are sitting on
The AI Code Audit is £495, fixed.
Tell us roughly what you built and how many people use it. If an audit is not the right thing for you, we will say so.
What the report covers:
- What is actually inside the app bundle you ship to users
- What your backend accepts from a modified or intercepted client
- What the app stores on the device, and what it collects
- Whether your store declarations match what the app really does
We reply within one working day.
