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

The "No Access-Control-Allow-Origin" error is a common issue in web development that occurs when a browser blocks a cross-origin request due to missing or mismatched CORS headers. There are two types of errors: the CORS header is missing or does not match the expected value. If you own the API, you can fix the error by adding the Access-Control-Allow-Origin header and specifying the allowed origin. You can implement CORS in your backend technology, such as Express, by using the cors middleware. If you don't own the API, you can route the request through your backend by creating a dedicated endpoint to fetch the target API. This way, the request is made from the backend, bypassing CORS restrictions. Another option is to use a CORS proxy, which fetches the resource on your behalf and returns the data with the appropriate CORS header. Corsfix is an example of a CORS proxy that can be used to solve the error. Depending on your situation, you can either make changes to your backend or use a CORS proxy to fix the error. By understanding the causes and solutions to the "No Access-Control-Allow-Origin" error, you can overcome this common obstacle in web development.