If someone asks how your app was built and the honest answer is "AI built most of it," that sentence is doing too much work. It could mean three very different things, and each one leaves a different kind of mess behind.
A founder who typed prompts into Lovable and got a live app with logins and a database has a different problem than a founder who typed prompts into v0 and got a beautiful screen. Both have a different problem than a founder whose developer has spent a long stretch of time accepting Cursor's suggestions. Same phrase, three categories, three blind spots. Knowing which one you actually used tells you, roughly, what is wrong before anyone opens the code.
The short answer
- Full-stack AI builders (Lovable, Bolt, Replit) generate a working front end and a working backend together. The blind spot hides in the backend: auth, data rules, and whether it can survive real traffic.
- UI generators (v0) generate only the front end. The blind spot is not a weak backend, it is no backend at all, dressed up in a finished-looking screen.
- AI-assisted IDEs (Cursor) put a developer in the loop, suggestion by suggestion. The blind spot is architectural drift: a codebase built from many individually reasonable choices that never add up to a coherent design.
- The category you used predicts the failure mode more reliably than the tool's marketing does.
- The fix is a targeted hardening or cleanup pass matched to that category, almost never a rebuild.
Why the category matters more than the tool name
Most founders describe their stack by the tool, not the category: "I used Lovable" or "I used Cursor." That is natural, but it hides the more useful fact, which is what kind of thing the tool actually produced.
A full-stack builder hands you an app. A UI generator hands you a screen. An AI-assisted IDE hands you whatever a developer, working with an assistant, chose to build. Those are three different starting points for a rescue, and mixing them up wastes time. Auditing a v0 project for weak Supabase rules is a wasted afternoon, because there usually is no Supabase to audit. Auditing a Lovable project for missing backend logic is also a waste, because the logic is there. The question is whether it is safe.
Full-stack builders: the backend you didn't see
Lovable, Bolt, and Replit each generate a complete application in one motion: a working front end plus a working backend, often with authentication, a database, and storage already wired up. This is genuinely impressive, and it is also exactly why it is risky. The app looks finished because it functionally is, which makes founders trust it more than they should.
The recurring gap with Lovable apps is backend access rules left open. Lovable builds on Supabase, and if row-level security is off or misconfigured, any visitor can read or write data that should be private. Nothing looks broken. The app works. It is simply not locked.
The recurring gap with Bolt apps is that the backend was built for the in-browser sandbox it runs in, not for real traffic, real secrets, or a production deployment. It behaves perfectly in the preview, because the preview is the environment it was designed for.
The recurring gap with Replit apps is similar: the app was scaffolded and hosted inside Replit's own environment, with secrets handled casually because it never had to leave that sandbox. Getting it onto infrastructure you actually own, with proper secrets management, is a separate piece of work nobody did.
If you used a full-stack builder, assume the front end is in reasonable shape and the real question is what the backend is quietly allowing.
UI generators: the backend that never existed
v0 is a different category entirely, and it is worth being precise about that, because the confusion here causes real damage. v0 generates React and Next.js components styled with Tailwind and shadcn/ui. It is front-end focused by design. It does not generate a database, authentication, or business logic.
The blind spot is not a weak backend. It is the absence of one, hidden behind a screen polished enough that it reads as a finished product. Buttons that do not save anything. Forms that do not go anywhere. Data that looks real but is hardcoded into the component. A founder who has not built software before can look at this and reasonably believe the hard part is done, when the hard part has not started.
If you used a UI generator, the honest question is not "what's wrong with my backend." It is "I need a backend, and I need it designed to match the interface I already have."
AI-assisted IDEs: a developer in the loop, drifting
Cursor is not a full-app generator at all. It is a code editor where a developer accepts, edits, or rejects AI suggestions line by line, or directs an agent mode through a task. A person is still making the calls. That sounds safer, and in one sense it is: someone was watching.
But the risk with Cursor is not a missing layer, it is an accumulation. Many individually sensible suggestions, accepted under deadline pressure, without a shared architectural view, tend to produce a codebase where several different files solve the same problem in several different ways. Occasional hallucinated APIs slip through review. Tests are often the first thing skipped, because the code "obviously works" when you write it, and nobody circles back. None of this shows up as one dramatic bug. It shows up as a codebase that gets slower and scarier to change every month, until a task that should take a day takes a week because nobody can predict what else it will touch.
If you used an AI-assisted IDE, you are less likely to have a single glaring security hole and more likely to have a structural problem: real code, written by a real developer, that has drifted away from any single coherent shape.
Which category are you actually in?
A quick way to check: did a prompt produce a whole deployed app with a login screen and a database on its own? That is a full-stack builder. Did a prompt produce components you then had to wire up to real data yourself? That is a UI generator. Did a developer sit in an editor, accepting and shaping AI suggestions over weeks or months? That is an AI-assisted IDE, and the category most likely to actually have a person you can ask.
Some projects are a mix. A v0 screen dropped into a Lovable backend. A Bolt prototype later handed to a developer working in Cursor. When that happens, the useful move is to trace which layer came from which category, because the risk profile changes layer by layer, not project by project.
What the category implies for the fix
For a full-stack builder, the work centers on the backend: locking down data access, checking authentication is enforced on the server and not just hidden in the interface, and making sure the app can take real traffic and real secrets safely.
For a UI generator, the work centers on building what does not exist yet: a real data model, real authentication, and business logic that fits the interface already designed, rather than fighting it.
For an AI-assisted IDE, the work centers on structure: finding the riskiest, most duplicated pieces, pulling them into one place, and adding the tests that let a team change the code without guessing. The starting point across all three tends to be the same short exercise: an honest look at what is actually there.
Key takeaways
- "AI built it" is not one risk profile. It is at least three, and they fail in different ways.
- Full-stack builders (Lovable, Bolt, Replit) hide the risk in a backend that looks finished but may not be locked down or production-ready.
- UI generators (v0) hide the fact that there is no backend at all behind a polished screen.
- AI-assisted IDEs (Cursor) put a developer in the loop, but risk architectural drift across a growing codebase.
- Knowing your category tells you where to look first, before you spend money guessing.
A calm next step
If you are not sure which category your project falls into, or you know exactly which tool you used and just want an honest read on what it left behind, that is a normal starting point, not a failure. We work across all five: see how we approach each one at /fix, including Lovable, Bolt, v0, Cursor, and Replit. Start with a free written first read, or read more about how we work at how we work and get in touch with what you built and what worries you.