Bolt·Fixdeployintermediate

CORS Error in Bolt.new App

Quick Answer

How do I fix CORS Error in Bolt.new App?

Calling an external API directly from the browser gets blocked by CORS policy. The browser prevents cross-origin requests for security. Start with "Create a server-side proxy" before making broader code changes.

Fix signals

What this answers: Why cors error in bolt.new app happens and what to change first.
Fastest move: Create a server-side proxy
Use this page if: 'Access-Control-Allow-Origin' error in console

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.

Bolt reviews

Open this when the prototype came fast but the rebuild cost is starting to show up in auth, deploy, or state problems.

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Bolt vs v0

Open this when the real decision is whether you still need a browser-first prototype tool or a stronger frontend base.

Open this next →

Fillout vs Typeform

Open this when forms, onboarding, intake, or checkout are the next workflow layer breaking after the app shell is already in place.

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Deploy hub

Open this when the build error is one symptom and the bigger problem is your production handoff and hosting workflow.

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Cursor review

Open this when deploy pain is pushing you toward a more code-first workflow with tighter control.

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Quick Fix Summary

Most likely cause	Calling an external API directly from the browser gets blocked by CORS policy. The browser prevents cross-origin requests for security.
Fastest fix	Create a server-side proxy
Use this page if	'Access-Control-Allow-Origin' error in console

You're in the right place if...

!'Access-Control-Allow-Origin' error in console
!API calls work in Postman but fail in browser
!Network requests blocked

Why this happens

Calling an external API directly from the browser gets blocked by CORS policy. The browser prevents cross-origin requests for security.

Fix

Create a server-side proxy

Tell Bolt to route API calls through a server-side endpoint:

Copy this prompt

I'm getting a CORS error when calling [API name]. Please create a server-side API route that proxies the request:

/api/[endpoint-name] → calls external API

The browser calls our API route instead, avoiding CORS restrictions.

Prevent this next time

Never call external APIs directly from the browser. Always create a server-side API route that proxies the request.