Understanding HTTP status codes is crucial for web developers. These codes provide insight into the status of a request made to a server, helping you diagnose and troubleshoot issues effectively. Here’s a comprehensive guide to 18 essential HTTP status codes that you need to know.

1. 200 OK

Request Succeeded

The 200 status code indicates that the request has succeeded. The server has successfully processed the request, and the result is returned in the response.

2. 201 Created

Resource Created

The 201 status code signifies that the request has been fulfilled and a new resource has been created as a result. This is typically the response after a POST request.

3. 202 Accepted

Accepted Request

The 202 status code means that the request has been accepted for processing, but the processing has not been completed. This is often used for asynchronous operations.

4. 204 No Content

No Content

The 204 status code indicates that the server has successfully processed the request, but there is no content to send in the response. This is common for DELETE requests.

5. 301 Moved Permanently

Resource Moved Permanently

The 301 status code tells the client that the resource requested has been permanently moved to a new URL. The client should use the new URL for future requests.

6. 302 Found

Temporarily Moved

The 302 status code indicates that the resource requested is temporarily located at a different URL. The client should continue to use the original URL for future requests.

7. 304 Not Modified

Not Modified

The 304 status code means that the resource has not been modified since the last request. The client can use the cached version of the resource.

8. 400 Bad Request

Bad Request Error

The 400 status code indicates that the server could not understand the request due to invalid syntax. This is a client-side error.

9. 401 Unauthorized

Needs Authentication

The 401 status code means that the request requires user authentication. The client must authenticate itself to get the requested response.

10. 403 Forbidden

Access Forbidden

The 403 status code indicates that the server understands the request but refuses to authorize it. This is often due to insufficient permissions.

11. 404 Not Found

Resource Not Found

The 404 status code means that the server cannot find the requested resource. This is a common error when the URL is incorrect or the resource does not exist.

12. 405 Method Not Allowed

Method Not Allowed

The 405 status code indicates that the request method is not supported for the requested resource. For example, using a POST method on a read-only resource.

13. 408 Request Timeout

Request Timed Out

The 408 status code means that the server timed out waiting for the request. This can happen if the request takes too long to complete.

14. 500 Internal Server Error

Server Error

The 500 status code indicates that the server encountered an unexpected condition that prevented it from fulfilling the request. This is a generic server error message.

15. 501 Not Implemented

Not Implemented

The 501 status code means that the server does not support the functionality required to fulfill the request. This indicates that the server cannot recognize the request method.

16. 502 Bad Gateway

Bad Gateway Error

The 502 status code indicates that the server, while acting as a gateway or proxy, received an invalid response from the upstream server.

17. 503 Service Unavailable

Service Unavailable

The 503 status code means that the server is currently unable to handle the request due to temporary overloading or maintenance of the server.

18. 504 Gateway Timeout

Gateway Timeout

The 504 status code indicates that the server, while acting as a gateway or proxy, did not receive a timely response from the upstream server. This typically happens when the server is down or not responding.

Conclusion

HTTP status codes are vital for understanding the outcome of a request and diagnosing issues in web development. Familiarizing yourself with these codes will help you quickly identify and resolve problems, ensuring a smoother development process and a better user experience.

By mastering these essential HTTP status codes, you can enhance your ability to debug issues, optimize your server-client interactions, and improve the overall functionality of your web applications.