Lovable·Fixsecurityintermediate

A Secret API Key Is Exposed in the Frontend of a Lovable App

Quick Answer

How do I fix A Secret API Key Is Exposed in the Frontend of a Lovable App?

A server-only secret was placed in client-side code, a NEXT_PUBLIC variable, or a browser fetch call. Once bundled into the frontend, it is effectively public. Start with "Rotate the leaked key immediately" before making broader code changes.

Fix signals

High stakes: The app leaked a secret because the architecture put trust in the client.
Check next: Server-only env usage, rotated secrets, and downstream abuse.
Best follow-up: Move secret work server-side and rotate everything exposed.

If this keeps happening

Open the next decision, not just the patch

Use these when the current fix is helpful, but the real answer is a better tool choice, a cleaner workflow layer, or a more trustworthy launch path.

Lovable reviews

Open this when the same full-stack MVP failures keep repeating and you need a harder answer on whether Lovable is still the right bet.

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Cursor review

Open this when the pattern behind the bug is really about generated speed versus owning more of the stack in code.

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Deploy hub

Open this when the fix is exposing a bigger production handoff problem, not just one broken feature.

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Tool picker

Open this when the repeated bug is making you question the whole stack choice instead of the latest patch.

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Firecrawl review

Open this when the app also needs live web data and the next stack decision is no longer only about the builder itself.

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Quick Fix Summary

Most likely cause	A server-only secret was placed in client-side code, a NEXT_PUBLIC variable, or a browser fetch call. Once bundled into the frontend, it is effectively public.
Fastest fix	Rotate the leaked key immediately
Use this page if	You can see a secret key in the browser source or network tab

You're in the right place if...

!You can see a secret key in the browser source or network tab
!A key starting with sk_, service_role, or Bearer is shipped to the client
!Abuse or unexpected API usage appears after launch

Why this happens

A server-only secret was placed in client-side code, a NEXT_PUBLIC variable, or a browser fetch call. Once bundled into the frontend, it is effectively public.

Fix

Rotate the leaked key immediately

Do not leave the exposed key active. Create a replacement in the provider dashboard, update the server-side secret, and revoke the leaked one.

Move the API call behind a server route

Any request needing a secret belongs in an API route, Edge Function, or backend action that the browser calls indirectly.

Audit env variable prefixes

Anything prefixed with NEXT_PUBLIC_ is exposed to the browser. Keep only genuinely public values there.

// Safe in browser:
NEXT_PUBLIC_SUPABASE_URL=...

// Never in browser:
STRIPE_SECRET_KEY=...
SUPABASE_SERVICE_ROLE_KEY=...
OPENAI_API_KEY=...

Patch the generated code path

Tell Lovable to move all secret-bearing calls out of the frontend.

Copy this prompt

Audit this app for any secret keys, bearer tokens, service role keys, or provider SDK calls that run in the browser. Move them to secure server-side routes and update the frontend to call those routes instead.

Prevent this next time

If a value can spend money, bypass auth, or write privileged data, it does not belong in client code.