What is the difference between 401 and 403?

401 Unauthorized means the request lacks valid authentication credentials — the user is not logged in or the token is invalid. 403 Forbidden means the server understood the request but refuses to authorize it — the user is authenticated but lacks permission.

When should an API return 404 vs 400?

Return 404 when a requested resource genuinely does not exist (GET /users/999 where user 999 doesn't exist). Return 400 for malformed requests with invalid parameters or missing required fields.

What is the difference between 301 and 302 redirects?

301 Moved Permanently tells browsers and crawlers to permanently update their records — they cache the redirect. 302 Found is a temporary redirect that should be rechecked on each request. SEO link equity passes through 301s but not reliably through 302s.

Σπίτι ΕργαλείαHTTP Status Codes

Κωδικοί Κατάστασης HTTP

Name: Κωδικοί Κατάστασης HTTP
Rating: 4.8 (120 reviews)
Author: DailyDevTools

Λίστα αναφοράς κωδικών κατάστασης HTTP

100

Continue

The server has received the request headers and the client should proceed to send the request body.

200

The request succeeded. The result meaning depends on the HTTP method.

201

Created

The request succeeded, and a new resource was created as a result.

204

No Content

There is no content to send for this request, but the headers may be useful.

301

Moved Permanently

The URL of the requested resource has been changed permanently.

302

Found

The URI of requested resource has been changed temporarily.

304

Not Modified

Used for caching purposes. It tells the client that the response has not been modified.

400

Bad Request

The server cannot or will not process the request due to an apparent client error.

401

Unauthorized

The request requires user authentication.

403

Forbidden

The client does not have access rights to the content.

404

Not Found

The server can not find the requested resource.

405

Method Not Allowed

The request method is known by the server but is not supported by the target resource.

429

Too Many Requests

The user has sent too many requests in a given amount of time.

500

Internal Server Error

The server has encountered a situation it does not know how to handle.

502

Bad Gateway

The server received an invalid response from the upstream server.

503

Service Unavailable

The server is not ready to handle the request (overloaded or maintenance).

504

Gateway Timeout

The server did not get a response in time from the upstream server.

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What is HTTP Status Codes?

HTTP status codes are 3-digit numbers that web servers return to indicate the result of a request. Knowing what 404, 500, 301, 401, 403, and 429 mean — and when to use each — is essential for API development and debugging. DailyDevTools' HTTP Status Code Reference provides a searchable list of all standard status codes with descriptions, common causes, and suggested fixes.

How to use HTTP Status Codes

1Search for any status code (e.g., 404) or keyword (e.g., 'unauthorized') in the search box
2Browse codes by category: 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, 5xx Server Error
3Click any status code to expand its full description, common causes, and how to resolve it
4Use the code as a quick reference when debugging API responses in your applications

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