You don't need to see 5,000 APIs to know some are better than others. One of the reasons is the attention the API providers have paid to the designs of their APIs. Below are three people summarizing popular approaches and helping you think about API design, whether you're using someone else's or planning your own offering.
Apperian encourages you to think about extensibility in the video embedded below:
Among the tips are to focus on the most scenarios and aim for self-documenting APIs.
Good APIs the Google Way
Google's Joshua Bloch has a great presentation (PDF). His general principles should not be skipped:
- API Should Do One Thing and Do it Well
- API Should Be As Small As Possible But
- Implementation Should Not Impact API
- Minimize Accessibility of Everything
- Names Matter–API is a Little Languag
- Documentation Matters
- Document Religiously
- Consider Performance Consequences of
API Design Decisions
- Effects of API Design Decisions on
Performance are Real and Permanent
- API Must Coexist Peacefully with Platform
A good overview of common approaches to APIs. Includes explanations of HTTP GET/POST, *-RPC, SOAP, "REST" (yes, in quotes) and Hypermedia.
I'm sure there are many other great examples of API design best practices. I hope you'll add your favorites in the comments.