This article will focus on designing an API, but many of these issues are present in existing APIs as well.
1) Not using HTTP status codes correctly
HTTP status codes are very important for two reasons: they tell you what happened with your request, and they allow you to make decisions based on that information. For example, if you send a POST request to create something and receive a 201 Created response code back, it means that resource was created successfully. If instead you get a 409 Conflict , then there was already something else at that URI which prevented your creation from happening (e.g
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