How do I securely call third-party APIs?
Last checked 31 Aug 2026
Short answer
Keep every API key and secret server-side in a Lovable Cloud/Supabase server function, never in front-end code, and have your UI call that function instead of the third-party API directly.
The core rule
Anything shipped to the browser — including environment variables baked into a front-end build — can be read by anyone who opens developer tools. API keys and secrets must live server-side: in a server function (Edge Function) backed by Lovable Cloud or your own Supabase project.
The pattern to ask for
"Create a server function that calls [API]'s endpoint using my API key stored as a secret, and have the front end call that server function instead of the API directly."
- Store the credential as a secret via Lovable (ask, don't hardcode it).
- Build a server function that makes the actual third-party call.
- Your React components call your own server function's URL, which then calls out to the third party.
Additional layers worth asking for
- Input validation on the server function, so it doesn't blindly forward whatever the client sends.
- Rate limiting per user, especially for paid third-party APIs (AI models, SMS, email) where abuse costs you money.
- Row-level security on any database tables involved, so users can only read/write their own data even if they inspect the network requests.
- Logging of failures so you can debug without exposing raw error details (which sometimes leak provider internals) to the user.
What usually goes wrong
- A key pasted directly into a component "just to test it", then forgotten about and shipped to production.
- Assuming HTTPS alone makes a front-end-embedded key safe — it doesn't; the key is visible in the compiled JavaScript regardless of transport encryption.
- Server functions with no input validation, letting a malicious client trigger unintended (and potentially costly) third-party calls.
- Forgetting that CORS restrictions often mean you can't call many third-party APIs directly from the browser anyway — another reason the server-function pattern is the default.
If you're handling anything sensitive — payment data, health information, regulated industries — get PromptSites.com to review the integration before launch.
Sources
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