Recently Lorna Mitchell asked the wide world of Twitter about some of their recommendations of things not to do when creating an API. In this new post to her site, she gathers together those responses including comments about documentation, consistency and response codes.

Recently I tweeted as a #linktuesday link the 10 Worst API Practices post from ProgrammableWeb. Today, in search of some concrete examples of APIs implementing unhelpful antipatterns, I sent out a tweet for help: "What's the most frustrating inconsistent/misleading bit of API you've seen? Looking for cautionary tales!" [...] In the raft of responses (and thankyou all, this was fabulous, helpful and entertaining in equal parts!), there were some definite patterns that I'd like to share with you, in no particular order.

Comments came in from all over and talked about things like:

• Response codes not matching the content (ex. 200 on an error)
• NullPointerExceptions
• Different endpoints for single vs collections
• Order-sensitive XML in requests
• Poor error handling
• Bad documentation
• Incorrect content type handling

So there you have it, the sins to avoid in your own APIs. If you've encountered any of these, please accept my condolences.