Your API’s developer experience (DX) matters as much as your web site’s user experience: making people more successful ultimately makes more people successful. For HTTP APIs, a good DX doesn’t only come from HTTP’s simplicity, but also from its depth. This presentation introduces a parody API that makes every classic mistake, and shows how they lead to Dr Evil’s inevitable downfall.
Further reading: Use HTTP error handling in APIs and HTTP client error status code checklist.