API HTTP Error Code
API Testing, API, 2025
HTTP Status Code Flashcards
1xx Informational
2xx Success
3xx Redirection
4xx Client Error
5xx Server Error
Quick Stats
4
Informational
10
Success
9
Redirection
33
Client Error
12
Server Error
🟡 1xx - Informational Responses
100
Continue
Server received request headers and client should proceed with request body
101
Switching Protocols
Server is switching to protocol requested by client in Upgrade header
102
Processing
Server is processing the request but no response is available yet
103
Early Hints
Server is sending preliminary response headers while preparing final response
🟢 2xx - Success Responses
200
OK
Request was successful and server returned requested data
201
Created
Request was successful and a new resource was created
202
Accepted
Request was received but processing is not yet complete
203
Non-Authoritative Info
Request successful but response contains modified information from proxy/cache
204
No Content
Request successful but no content to return in response body
205
Reset Content
Request successful and client should reset the form/document
206
Partial Content
Server is delivering only part of resource due to Range header
207
Multi-Status
Multiple operations performed with individual status for each in response body
208
Already Reported
Resource was already mentioned earlier in the same response
226
IM Used
Server fulfilled GET request using instance manipulations
🟣 3xx - Redirection Messages
300
Multiple Choices
Multiple options available for the resource - client should choose one
301
Moved Permanently
Resource has permanently moved to new URL specified in Location header
302
Found
Resource temporarily moved to different URL specified in Location header
303
See Other
Response can be found at different URI using GET method
304
Not Modified
Cached version is still valid - no modification since last request
305
Use Proxy
Request must be made through specified proxy (deprecated)
307
Temporary Redirect
Resource temporarily moved but client must use same HTTP method
308
Permanent Redirect
Resource permanently moved but client must use same HTTP method
🟠 4xx - Client Error Responses
400
Bad Request
Server cannot process request due to malformed syntax or invalid data
401
Unauthorized
Authentication is required to access the requested resource
402
Payment Required
Reserved for future use in digital payment systems
403
Forbidden
Server understands request but refuses to authorize access
404
Not Found
Requested resource could not be found on the server
405
Method Not Allowed
HTTP method used is not supported for this resource
406
Not Acceptable
Server cannot produce response matching Accept headers criteria
407
Proxy Auth Required
Client must authenticate with proxy before accessing resource
408
Request Timeout
Server timed out waiting for complete request from client
409
Conflict
Request conflicts with current state of target resource
410
Gone
Requested resource is no longer available and will not be available again
411
Length Required
Server requires Content-Length header to process request
412
Precondition Failed
Server does not meet preconditions specified in request headers
413
Payload Too Large
Request payload exceeds server's size limits
414
URI Too Long
Request URI is longer than server is willing to interpret
415
Unsupported Media Type
Media type of request payload is not supported by server
416
Range Not Satisfiable
Range specified in Range header cannot be fulfilled
417
Expectation Failed
Server cannot meet requirements of Expect request header
418
I'm a Teapot
April Fool's joke - server refuses to brew coffee because it's a teapot
421
Misdirected Request
Request was directed at server that cannot produce response
422
Unprocessable Entity
Request is well-formed but contains semantic errors
423
Locked
Resource being accessed is locked and cannot be modified
424
Failed Dependency
Request failed because it depends on another failed request
425
Too Early
Server unwilling to process request that might be replayed
426
Upgrade Required
Client must switch to different protocol to continue
428
Precondition Required
Server requires request to be conditional with appropriate headers
429
Too Many Requests
Client has exceeded rate limit for requests in given time period
431
Request Header Fields Too Large
Request header fields are too large for server to process
451
Unavailable For Legal Reasons
Resource unavailable due to legal restrictions
🔴 5xx - Server Error Responses
500
Internal Server Error
Server encountered unexpected condition preventing request fulfillment
501
Not Implemented
Server does not support functionality required to fulfill request
502
Bad Gateway
Server acting as gateway received invalid response from upstream server
503
Service Unavailable
Server temporarily unable to handle request due to overload or maintenance
504
Gateway Timeout
Server acting as gateway did not receive timely response from upstream
505
HTTP Version Not Supported
HTTP version used in request is not supported by server
506
Variant Also Negotiates
Server has internal configuration error in content negotiation
507
Insufficient Storage
Server cannot store representation needed to complete request
508
Loop Detected
Server detected infinite loop while processing request
510
Not Extended
Further extensions required for server to fulfill request
511
Network Authentication Required
Client needs to authenticate to gain network access
599
Network Connect Timeout Error
Network connection timeout occurred while processing request