What is an HTTP status code?

An HTTP status code is a three-digit number returned by a web server to indicate the result of a client's request. The first digit defines the category: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error.

What is the difference between 301 and 302?

A 301 Moved Permanently tells the client and search engines that the resource has permanently moved to the new URL — it is cacheable and search engines transfer link equity. A 302 Found indicates a temporary redirect; clients should continue using the original URL for future requests.

What does 404 Not Found mean?

The server could not find the requested resource. It may have been deleted, moved without a redirect, or the URL was typed incorrectly. 404 responses are not cached by default and do not transfer any link equity.

What is the difference between 401 and 403?

401 Unauthorized means the request lacks valid authentication credentials — the server wants the client to authenticate. 403 Forbidden means the server understood the request and the client is authenticated (or authentication is not required), but access is denied.

When should I use 200 vs 204?

200 OK returns a response body. 204 No Content indicates the action succeeded but there is nothing to return (common for DELETE or PUT endpoints where the client does not need a response body).

What is a 429 status code?

429 Too Many Requests is returned when the client has sent too many requests in a given time window (rate limiting). The server may include a Retry-After header indicating when the client can retry.

What does 503 Service Unavailable mean?

The server is temporarily unable to handle the request, often due to maintenance or being overloaded. Unlike 500, a 503 implies the condition is temporary. Servers should include a Retry-After header when the recovery time is known.

Are HTTP status codes the same as REST API status codes?

REST APIs use the same HTTP status codes defined in the HTTP specification. However, API designers choose which codes to use for which situations. The HTTP Status Reference shows all standard codes; how a specific API maps them to its operations is defined by that API's documentation.

Web Tools /

HTTP status code reference

All standard HTTP status codes with explanations and use cases. Filter by category or search by code or keyword.

How to use

Type a status code (e.g. 418) or keyword (e.g. redirect) in the search box.
Or click a category button to filter by 1xx, 2xx, 3xx, 4xx, or 5xx.
Click any row to expand the full description and cacheability note.

Common use cases

SEO audits — identify 301 vs 302 redirects and their link equity impact.
API debugging — understand which 4xx code your server should return for each error type.
Cache configuration — know which codes are cacheable by default (200, 301, 410) versus not (302, 307).
Monitoring setup — configure alerts for 5xx server error codes.

Also see: DNS Lookup to check A/MX records, Robots.txt Validator to confirm crawl rules.

Preguntas frecuentes

What is an HTTP status code?: An HTTP status code is a three-digit number returned by a web server to indicate the result of a client's request. The first digit defines the category: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error.
What is the difference between 301 and 302?: A 301 Moved Permanently tells the client and search engines that the resource has permanently moved to the new URL — it is cacheable and search engines transfer link equity. A 302 Found indicates a temporary redirect; clients should continue using the original URL for future requests.
What does 404 Not Found mean?: The server could not find the requested resource. It may have been deleted, moved without a redirect, or the URL was typed incorrectly. 404 responses are not cached by default and do not transfer any link equity.
What is the difference between 401 and 403?: 401 Unauthorized means the request lacks valid authentication credentials — the server wants the client to authenticate. 403 Forbidden means the server understood the request and the client is authenticated (or authentication is not required), but access is denied.
When should I use 200 vs 204?: 200 OK returns a response body. 204 No Content indicates the action succeeded but there is nothing to return (common for DELETE or PUT endpoints where the client does not need a response body).
What is a 429 status code?: 429 Too Many Requests is returned when the client has sent too many requests in a given time window (rate limiting). The server may include a Retry-After header indicating when the client can retry.
What does 503 Service Unavailable mean?: The server is temporarily unable to handle the request, often due to maintenance or being overloaded. Unlike 500, a 503 implies the condition is temporary. Servers should include a Retry-After header when the recovery time is known.
Are HTTP status codes the same as REST API status codes?: REST APIs use the same HTTP status codes defined in the HTTP specification. However, API designers choose which codes to use for which situations. The HTTP Status Reference shows all standard codes; how a specific API maps them to its operations is defined by that API's documentation.

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