How to Fix the “No ‘Access-Control-Allow-Origin’ Header” Error

Reynaldi • November 22, 2025

In this guide, you’ll learn how to instantly fix CORS errors when trying to access an API, understand why they happen, and compare solutions so you can quickly get back to building your website.

Access to fetch at 'https://example.com/' from origin 'http://localhost:3000'
has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present
on the requested resource.

The “Access to fetch blocked by CORS policy” error in your browser console

Instant Fix (30 seconds)

Use Corsfix to instantly solve your “No ‘Access-Control-Allow-Origin’ header” errors. Simply add the proxy URL before your API calls, and you’ll be able to connect to the API without errors.

// instead of
fetch('https://api.example.com/data');

// use Corsfix
fetch('https://proxy.corsfix.com/?' + 'https://api.example.com/data');

This solution works instantly in development environments (localhost) without any registration.

For live websites, set up your domain (takes 30 seconds), then your website can access the data without CORS errors.

Why do CORS errors happen?

CORS (Cross-Origin Resource Sharing) errors happen because the target API you’re trying to call does not return the CORS headers. Without these headers, your browser won’t be able to access that API’s data.

Access-Control-Allow-Origin: https://website.com

The Access-Control-Allow-Origin header

This header controls whether a website can access the API. However, not all APIs include this header, which is why the error happens in the first place.

Comparing Solutions

Using Corsfix CORS Proxy

With Corsfix, you can solve the “No ‘Access-Control-Allow-Origin’ Header” issues instantly by simply adding the proxy URL before your target API. Our server will relay your request and return it to you with the appropriate CORS headers, solving the errors.

// GET request
fetch("https://proxy.corsfix.com/?https://api.example.com/users")
  .then((response) => response.json())
  .then((data) => console.log(data));

// POST request
fetch("https://proxy.corsfix.com/?https://api.example.com/users", {
  method: "POST",
  body: JSON.stringify({ name: "John" }),
  headers: {
    "Content-Type": "application/json",
  },
});

Code example for fixing CORS error

Setting up your own backend

If you have access to the API server causing the CORS error, you would need to add the missing CORS headers:

Access-Control-Allow-Origin: https://your-website.com

Adding CORS header for your own API

However, when working with APIs you don’t control, beside using Corsfix, you’d need to build your own proxy server.

This means you’ll need to handle your own infrastructure, manage different HTTP methods (GET, POST, PUT, DELETE), deal with authentication headers, ensure your server stays online 24/7, manage server hosting costs, SSL certificates, and ongoing maintenance.

Temporary Solution

A common solution people find when trying to fix CORS errors is using browser extensions to disable or unblock CORS. However, this is not suitable for production.

Browser extensions for unblocking CORS

This is a temporary solution that only works on your own machine during development. When your website visitors try to access your site, they’ll still encounter CORS errors because these fixes don’t work for end users in production.

Conclusion

Use Corsfix to instantly solve “No ‘Access-Control-Allow-Origin’ Header” errors. Understanding how CORS works is essential when working with third-party APIs, and knowing your options helps you choose the right solution.

Corsfix is free to get started, and you only need to upgrade when you go to production.