Do you know any one man SaaS app that are profitable?

I'm asking this because I'm considering starting a SaaS app as a side project, and I'm looking for some inspiration.

Thanks!

Note: this is was previously on HN here[1], but it's been few years, and I'm sure a lot of one person startups are thriving than before.

[1]: https://news.ycombinator.com/item?id=11924009