A searchable cheat sheet of HTTP status codes, common headers and MIME types.
Code
Name
Meaning
Header
Used in
Description & example
Extension
MIME type
Notes
Method
Safe
Idempotent
Request body
Response body
Cacheable
Purpose
Safe: does not change server state. Idempotent: repeating the request has the same effect as sending it once. *PATCH is not idempotent by definition but can be designed to be.