HTTP Status Code Cheat Sheet - From Informational (1xx) to Server Errors (5xx)

This article explores HTTP status codes, their categories, common examples, and their significance in web development.

5 mins read

HTTP Status Code Cheat Sheet - From Informational (1xx) to Server Errors (5xx)

In the vast world of the internet, HTTP (HyperText Transfer Protocol) is the backbone enabling communication between clients (browsers) and servers. An essential component of this communication is HTTP status codes, which inform users and developers about the results of their requests.

What Are HTTP Status Codes?

HTTP status codes are three-digit numbers returned by a server to indicate the result of an HTTP request. These codes provide a concise summary of the outcome, such as success, failure, or redirection.

For example, the status code 404 indicates a "Page Not Found" error, while 200 signifies a successful request.

Categories of HTTP Status Codes

HTTP status codes are divided into five categories, each representing a specific type of response:

Category	Code Range	Description
1xx	100–199	Informational responses
2xx	200–299	Success responses
3xx	300–399	Redirection messages
4xx	400–499	Client-side errors
5xx	500–599	Server-side errors

Complete List of HTTP Status Codes

1xx Informational Responses (Acknowledgment of Request Received)

Code	Description	Use Case	Example
100	Continue	Client should continue with the request.	Chunked uploads in HTTP/1.1.
101	Switching Protocols	Server switches to a different protocol.	HTTP to WebSocket protocol upgrade.
102	Processing	Server has received and is processing the request.	WebDAV operations requiring long processing times.
103	Early Hints	Used to send links for preload before final response.	Preloading scripts and stylesheets.
104	Request in Progress (Proposed)	Indicates a request is still being processed.	Reserved for future extensions.

2xx Successful Responses (Indicating Success)

Code	Description	Use Case	Example
200	OK	Standard response for a successful request.	Page loads successfully.
201	Created	Resource successfully created on the server.	New user registration API.
202	Accepted	Request accepted but not yet processed.	Queue-based API processing.
203	Non-Authoritative Information	Proxy-modified response with non-original metadata.	Proxies serving modified metadata.
204	No Content	Request successful with no content to return.	Updating user preferences silently.
205	Reset Content	Instructs the client to reset the form used for submission.	Clearing a search filter form.
206	Partial Content	Partial resource delivered for range requests.	Streaming video in chunks.
207	Multi-Status	Used in WebDAV for multiple responses in a single request.	Handling batch operations in WebDAV.
208	Already Reported	Avoids repeatedly reporting the same internal member resource.	Complex WebDAV operations.
226	IM Used	Server successfully applied an instance-manipulation to the response.	Delta encoding in HTTP.

3xx Redirection Responses (Further Action Needed)

Code	Description	Use Case	Example
300	Multiple Choices	Several resource representations available.	Redirecting users to localized versions of content.
301	Moved Permanently	Resource has been permanently moved to a new URL.	Website domain migration.
302	Found	Temporary redirect for the requested resource.	Redirecting during site maintenance.
303	See Other	Resource located at a different URI; client should use GET.	Redirecting after POST submission.
304	Not Modified	Cached version of resource is valid.	Optimizing web performance.
305	Use Proxy	Resource must be accessed through a proxy.	Deprecated due to security concerns.
306	Switch Proxy	Reserved; no longer used.	Historic placeholder for redirection.
307	Temporary Redirect	Temporary redirect without changing the HTTP method.	API endpoint undergoing testing.
308	Permanent Redirect	Permanent redirect with HTTP method unchanged.	SEO-friendly permanent URL redirection.

4xx Client Error Responses (Client Faults)

Code	Description	Use Case	Example
400	Bad Request	Malformed or invalid request syntax.	Missing query parameters in API calls.
401	Unauthorized	Authentication required but not provided.	Accessing protected resources.
402	Payment Required	Reserved for future use; sometimes used for paywalls.	Experimental use in APIs requiring payment.
403	Forbidden	Client is not allowed access to the resource.	Unauthorized access to admin panels.
404	Not Found	Resource could not be found.	Broken links or deleted pages.
405	Method Not Allowed	HTTP method not supported for the resource.	Using GET on an endpoint requiring POST.
406	Not Acceptable	Response content not acceptable based on headers.	Request for unsupported MIME types.
407	Proxy Authentication Required	Proxy authentication required.	Accessing content behind a proxy.
408	Request Timeout	Server timed out waiting for the request.	Poor network conditions.
409	Conflict	Request conflicts with the server’s state.	Editing the same document simultaneously.
410	Gone	Resource permanently removed without a forwarding address.	Deprecated or deleted API endpoints.
411	Length Required	Content-Length header missing.	Uploading files without specifying size.
412	Precondition Failed	Preconditions given in headers were false.	Conditional API requests with If-Match.
413	Payload Too Large	Request entity is larger than the server can handle.	Uploading oversized files.

5xx Server Error Responses (Server Faults)

Code	Description	Use Case	Example
500	Internal Server Error	Generic server error response.	Debugging unhandled server exceptions.
501	Not Implemented	Server does not support the functionality required.	API feature under development.
502	Bad Gateway	Invalid response from an upstream server.	Load balancer receiving corrupted data.
503	Service Unavailable	Server temporarily unavailable due to overload.	High-traffic spikes or maintenance.
504	Gateway Timeout	Upstream server failed to respond in time.	APIs with long processing times.
505	HTTP Version Not Supported	Server does not support the HTTP protocol version.	Legacy HTTP versions in modern servers.
506	Variant Also Negotiates	Circular references in negotiation process.	Misconfigured content negotiation.
507	Insufficient Storage	Server cannot store the representation.	Cloud-based file storage limits.
508	Loop Detected	Infinite loop detected during request processing.	Complex WebDAV queries.
510	Not Extended	Extensions required to fulfill the request.	Proprietary protocol extensions.

Reserved and Deprecated Codes

Code	Description	Status
418	I’m a teapot	Joke code from RFC 2324.
306	Switch Proxy	Reserved.
402	Payment Required	Reserved for future use.

Practical Examples of HTTP Status Codes

404 Not Found:

Example: Requesting .

Response:

301 Moved Permanently:

Example: Redirecting to .

200 OK:

Example: A successful API request for user data.

FAQs

What are HTTP status codes?
They are three-digit numbers indicating the result of an HTTP request.
Why are HTTP status codes important?
They help in debugging and improving user experience.
What does 302 Found mean?
It’s a temporary redirection to another URL.
How do I fix a 404 error?
Ensure the requested resource exists or implement proper redirects.
What is the difference between 4xx and 5xx?
4xx indicates client errors; 5xx signifies server issues.
What is 503 Service Unavailable?
It means the server is overloaded or under maintenance.
How do status codes impact SEO?
Codes like 301 and 404 can influence search engine rankings.
What does 204 No Content mean?
The server successfully processed the request but returns no content.
Why use 410 Gone instead of 404?
410 explicitly tells that the resource is permanently removed.
What does 500 Internal Server Error indicate?
It signifies a generic server issue requiring debugging.

To err is human, and while we have put our best effort into ensuring this content is accurate and helpful, there is always room for improvement! If you spot any errors or think of ways to make this article even better, please feel free to reach out. Your feedback is invaluable; we are always happy to learn from you. Thank you for reading!

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Edited by

Shivangi Vatsal

Sr. Associate Content Strategist @Unstop

I am a storyteller by nature. At Unstop, I tell stories ripe with promise and inspiration, and in life, I voice out the stories of our four-legged furry friends. Providing a prospect of a good life filled with equal opportunities to students and our pawsome buddies helps me sleep better at night. And for those rainy evenings, I turn to my colors.

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Engineering