We've developed an internal tool to remotely access iOS and Android log files (NSLog and logcat). We work remotely, so we always had issues debugging problems that we couldn't reproduce.

Initially it was just an internal experiment at Mobile Jazz and at some point we even thought killing it, but now after 3 years we're at €7300 MRR (~$8600/month) and growing consistently.

That said, we still haven't reached our break even point (also because we decided to invest more in marketing and supporting additional platforms) and it'll take us some more years to recuperate the time (=money) invested.

We've written about our story here: https://bugfender.com/blog/three-years-bugfender-9-5m-users/ and have provided an updated to revenue numbers and other statistics here: https://bugfender.com/blog/updates-from-bugfender-q2-2017/