Productive ToolboxHTTP Status Code Lookup
Searchable encyclopedia of all HTTP status codes with descriptions, use cases, and examples.
HTTP Status Code Lookup
Instantly search and understand all HTTP status codes. Perfect for developers debugging APIs, building web applications, or learning HTTP fundamentals.
Search HTTP Codes
Common Codes
All HTTP Status Codes
💡 Tips
- • Search by code number (404), name (Not Found), or keywords (redirect, server error)
- • Use category filters to narrow down results by status code type
- • Click on any code to see detailed explanation, use cases, and examples
Related tools
Complete HTTP Status Code Reference Guide
What are HTTP Status Codes?
HTTP status codes are three-digit numbers returned by web servers to indicate the result of a client's request. They provide essential information about whether a request was successful, encountered an error, or requires additional action. Understanding these codes is crucial for web developers, API engineers, and anyone working with web technologies.
HTTP Status Code Categories
1xx - Informational
Indicates that the request was received and understood. These are interim responses used to inform the client that the initial part of the request has been received.
2xx - Success
Indicates that the client's request was successfully received, understood, and accepted. These are the codes you want to see in your applications.
3xx - Redirection
Indicates that further action needs to be taken by the client to complete the request. Usually involves redirecting to a different URL.
4xx - Client Error
Indicates that the client seems to have made an error. The request contains bad syntax or cannot be fulfilled by the server.
5xx - Server Error
Indicates that the server failed to fulfill an apparently valid request. These errors originate from the server side and are not the client's fault.
Most Common HTTP Status Codes
200 OK
The most common success status. Indicates that the request has succeeded and the server has returned the requested data.
404 Not Found
The most famous error code. Indicates that the server cannot find the requested resource. Often seen when accessing broken links or deleted pages.
500 Internal Server Error
A generic server error indicating that something went wrong on the server side, but the server couldn't be more specific about the error condition.
Why HTTP Status Codes Matter
- •API Development: Proper status codes help clients understand request outcomes
- •SEO: Search engines use status codes to understand page availability
- •Debugging: Status codes provide immediate insight into what went wrong
- •User Experience: Proper error handling improves user satisfaction
- •Monitoring: Status codes help track application health and performance
Best Practices for HTTP Status Codes
- Be Specific: Use the most appropriate status code for each situation
- Consistency: Use the same status codes for similar scenarios across your API
- Documentation: Document which status codes your API returns and when
- Error Messages: Include helpful error messages in the response body
- Testing: Test that your application returns correct status codes
Tool Features
Search & Filter
- • Instant search by code number or keyword
- • Category filtering (1xx-5xx)
- • Fuzzy search across descriptions
Developer Tools
- • Copy code information to clipboard
- • Export detailed code explanations
- • Recent codes history
How to Look Up an HTTP Status Code
- 1Search for a code: Type a code number such as 404, a name such as Not Found, or a keyword such as redirect or timeout.
- 2Filter by class: Pick Informational (1xx), Success (2xx), Redirection (3xx), Client Error (4xx) or Server Error (5xx) to narrow the list, or use the buttons for the most common codes.
- 3Open the details: Click a code to see what it means, when servers send it and an example request and response.
- 4Copy or export: Copy the explanation to the clipboard or export it; codes you open are kept in Recent for quick access.
Frequently Asked Questions
What do the five classes of HTTP status codes mean?
The first digit gives the class: 1xx informational (the request is being processed), 2xx success, 3xx redirection (the client must go somewhere else), 4xx client error (the request is wrong or not allowed) and 5xx server error (the server failed on a valid request).
What is the difference between 401 and 403?
401 Unauthorized means the request has no valid credentials: log in or send a token and try again. 403 Forbidden means the server knows who you are but you are not allowed to access the resource, so logging in again will not help.
Should I use a 301 or 302 redirect?
Use 301 (or 308) when a page has moved permanently: browsers cache it and search engines pass ranking signals to the new URL. Use 302 (or 307) for temporary moves such as maintenance pages or A/B tests. 307 and 308 also keep the request method, so a POST stays a POST.
What is the difference between 404 and 410?
404 Not Found says nothing about whether the resource will return. 410 Gone says it was removed on purpose and will not come back, so search engines usually drop a 410 URL from their index sooner.
What causes a 500, 502, 503 or 504 error?
500 is a generic failure in the application itself. 502 Bad Gateway means a proxy or load balancer got an invalid response from the server behind it. 503 Service Unavailable means the server is overloaded or down for maintenance, often with a Retry-After header. 504 Gateway Timeout means the server behind the proxy took too long to answer.
When should an API return 400, 409, 422 or 429?
400 for a request that is malformed, such as invalid JSON. 422 when the syntax is fine but the data fails validation, for example a missing required field. 409 when the request conflicts with the current state, such as a duplicate username. 429 when the client has sent too many requests and must slow down.
How do status codes affect SEO?
Search engines index 200 pages, follow 301 and 308 redirects and pass their ranking signals on, and remove pages that keep returning 404 or 410. Repeated 5xx errors slow crawling, and a 503 tells crawlers an outage is temporary. A missing page that returns 200 is reported as a soft 404.
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