Mock data that never left
v0 makes screens look finished by inventing the data behind them: arrays hard-coded into components, TODOs where the database should be. The demo is a film set. Walls, no rooms.
Prototype rescue · v0
Make your v0 app production-ready.
Kyln turns v0 prototypes into production products. v0 generates the stack we build on ourselves: Next.js, React, Tailwind and Vercel. Senior London engineers finish what it started — data, auth, APIs and deploys. Reviews start at £1,500, and every price is public.
Next.js + React · shadcn/ui · Vercel · review from £1,500Where it breaks
Where v0 apps break.
v0 output is unusually good raw material: Next.js, React and shadcn/ui on Vercel, a genuinely production-grade stack. What it leaves out is the product underneath the interface. Six gaps come up again and again.
Why the last 20% is the hard partAuth as decoration
A sign-in page exists because you asked for one. Middleware enforcing it usually does not. Sessions, roles and protected server actions have to be designed, not generated.
Server actions that trust the client
Generated actions and API routes take whatever they are given: no validation, no rate limits, no ownership checks. Fine in a demo, expensive with strangers.
No data model
Each component invented its own shape for the same thing. Before a real database can go in, someone has to decide what the product's nouns actually are, and that is design work the generator skips.
State sprawl
Interactivity was bolted on screen by screen: useState everywhere, props drilled five levels deep, fetches in odd places. It works until two features need the same truth.
A deploy, not an operation
Vercel makes the first deploy easy. Environments, previews, error tracking and backups for whatever database gets added are still to build. A URL is not an operation.
The takeover
What survives, what changes.
v0 apps have the best salvage odds of any generator's, because the stack is already the right one. The review names what stays before anything gets replaced.
- The stack. Next.js on Vercel is what we would have chosen, so nothing needs porting.
- The components. shadcn/ui and Tailwind output slots into a production codebase with refactoring rather than replacement.
- The design direction. v0 is good at interfaces, and screens that test well stay.
- The momentum. Users and investors have seen the thing; the job is making it true underneath.
- A real data layer: schema, database, migrations, components rewired to it.
- Auth done properly: sessions, roles, middleware, protected server actions.
- Validation and rate limiting on every route that accepts input.
- State restructured around the data model instead of per-screen improvisation.
- Environments, error tracking and monitoring around the Vercel deploy.
- Tests on sign-up, payment and the paths that would hurt first.
The review · from £1,500 · about a week
First, someone senior reads it.
The entry point is a fixed-scope review, from £1,500, about a week from access to answer. A senior engineer reads the code. Josh, Kyln's founder, signs off every review.
You get a prioritised risk list tied to user and business impact, and a prescription with costs: salvage, refactor or rebuild. If the app is closer to ready than you feared, the review says that instead. The fee buys the honest answer, not a sales document. How that call gets made.
After the fix, most teams keep us on a care plan: hosting, monitoring, security updates and small changes, from £175 a month. Where the product needs someone to own where it goes next, not just keep it running, that can include fractional-CTO direction, from £3,000 a month.
What we read on a v0 app
- How much of the interface is wired to anything real: the mock-data census.
- Auth and middleware: what is actually protected, versus merely styled.
- Every server action and API route, for validation and ownership checks.
- The data model the components imply, and the schema it should become.
- Component and state structure: what refactors cleanly, what resists.
- The deploy, environments and the operational gaps around Vercel.
Production readiness · free · 2 minutes
Is your AI-built product safe to sell yet?
The Production Readiness Scorecard is a two-minute self-assessment that grades how close your product is to something you can safely put in front of paying customers, and names the risks standing in the way.
- 01
Describe what you built
One line on what your product does and how many paying customers it has today.
- 02
Answer honestly
A short set of pointed questions across auth, data, security, testing and operations.
- 03
Get your grade and risks
An instant letter grade and a “% ready” score, then your three biggest risks ranked worst-first, specific to what you’ve built.
Kyln
C
64% ready
Promising, but not safe to charge for yet. Three issues would bite a real customer first.
Top risks · worst first
- 01Admin endpoints have no authentication
- 02API keys are committed to the repository
- 03No automated tests run before deploy
Sample · your result is personalised
Other tools
Built with something else?
Prototype rescue · Lovable
Make your Lovable app production-ready
RLS policies, exposed keys, half-wired auth and one-environment deploys. The Lovable-specific route to production.
Read the Lovable page
Prototype rescue · BoltMake your Bolt app production-ready
Apps that run in the sandbox and break on deploy: secrets, Supabase security, silent regressions. The Bolt-specific route to production.
Read the Bolt page
Prototype rescue · all toolsReplit, Cursor, Claude Code or homegrown
The route is the same whatever generated the code: a senior review, then salvage, refactor or rebuild.
Start at the rescue hub
v0 rescue questions
Want to talk through the fit? Email contact@kyln.digital
Yes, that is the standard v0 job. The interface exists and the product behind it does not: database, auth, payments, APIs. Because v0 emits the stack we build on anyway, the work is finishing, not translating.