By Cursor-built apps most often break where nobody on the team understands the code: endpoints without access checks, no tests to catch what the next change breaks, and packages nobody vetted.
What Cursor builds
Cursor and Windsurf are AI code editors based on VS Code. Unlike app builders, they have no default stack or hosting: the project is ordinary code in your repository, in whatever language and framework the agent was asked for.
Where Cursor apps usually break
The flows that make money have tests
Sign-up, checkout and the core action. A few end-to-end tests catch most regressions from new prompts.
Dead code and duplicate components are removed
Search for components with near-identical names. Three versions of one button means three places to fix every bug.
Dependencies are current and audited
Run npm audit. Critical advisories in packages you ship should be fixed before launch.
One user cannot open another user's records
Sign in as user A, copy a request from the Network tab, and change the record ID to one that belongs to user B. You should get an error or an empty result.
Input is validated on the server
Forms that only check input in the browser accept anything sent directly to the API.
Errors reach you before users do
Add error monitoring and uptime alerts. If you learn about outages from customers, this is missing.
Check it yourself
- Ask someone outside the original session to explain how a request moves through the app. Gaps in that explanation are where bugs hide.
- Run
npm auditor your language's equivalent, and check that every imported package really exists and is maintained. - Add end-to-end tests for sign-up, checkout and the main action before the next round of AI changes.
- Review every endpoint for an access check.
When to call an engineer
Call an engineer when changes regularly break unrelated features, when you cannot explain how data is protected, or before a fundraise or a security questionnaire.
A one-off check costs $49 to $800. Fixing and hardening an app costs $1,500 to $15,000 and takes 1 to 8 weeks, based on the prices companies publish.
Top-rated companies for Cursor apps
Ranked by our score: published prices, scope of work, AI tools named, timing and a low-risk first step. How we score.
- 1Afterbuild Labs10.0/10Best for: A check before launchFree first step · from $49
- 2Redlab10.0/10Best for: A full rescue by one team that keeps buildingFree first step · from $490
- 3Vibe Code Rescue (Lev Arakelyan)9.0/10Best for: A one-off check and a cleanupFrom $299
Questions
Is Cursor code worse than code from app builders?
Not by default. It has fewer guardrails, so quality depends on review, tests and the person steering it.
Is a Windsurf project any different?
No. Windsurf's Cascade agent and Cursor's agent mode produce the same kind of project: ordinary code with no default stack, so the same checks apply. Projects written with Claude Code have their own guide.