Oh, it looks like we were competitors! I'm the founder of ReadMe.com, and we do API docs (as well as SDKs and more).

I don't really know why, specifically, we ended up being successful. I know I also had a lot of false starts – slightly iterating on the core idea until I hit something people were visibly excited about. I also knew it was a hard market, so I put a lot of my time and effort into non-engineering things. Hacker News was always good to us, especially as I was more vulnerable.

I'd love to hear more! I'm going to reach out privately :)

Overall, though, congrats on all the work you put in. It's incredibly hard to start a company and believe in yourself, and you should be proud!