How to Handle CORS Issues When Calling External APIs

Introduction

Cross-Origin Resource Sharing (CORS) is a security mechanism implemented in browsers to prevent malicious scripts from accessing potentially sensitive data from different origins. When a browser encounters a CORS request, it checks if the request is allowed based on the CORS headers sent by the server. If the request is not allowed, the browser will block it for security reasons. This can lead to errors when calling external APIs from your UI in the browser.

Resolving CORS Issues

There are several ways to resolve CORS issues. One common solution is to set the withCredentials property to false in your Axios call. This tells the browser that the request does not require credentials, and it will not send any cookies or other sensitive information with the request.

Another solution is to have the backend inject the Access-Control-Allow-Origin header into the response. This header tells the browser that the server allows requests from the specified origin. You can also specify multiple origins in the header, separated by commas.

Finally, if you need to access sensitive data from the server, you can use a proxy to send the request. A proxy server will forward the request to the server and handle the CORS headers on your behalf.

Conclusion

CORS issues can be frustrating, but they can be easily resolved by following the steps outlined in this article. By understanding how CORS works and how to configure your server and client code accordingly, you can ensure that your applications can communicate securely and efficiently across different origins.