Also, the api you have is great and I use it a lot. Good job!
One thing I worry about is how my data is being stored, and what you are tracking.
Rescuetime is useful enough to me that I haven't left for this reason, but I have looked at open source competing products that I can run myself. Could you make me more comfortable about the security and confidentiality of my data somehow?
In short we track the name of the application you're using, and the window title OR the URL of the website you're on (if you're in a recognized browser). We query the OS to detect what's in focus and whether or not the computer has gone idle to track time spent on a particular thing. We also use crowdsourced data collected over the years to understand what categories applications and websites are (meeting tools, communication tools, design/coding/business tools, etc.)
All of our data is never used individually, only analyzed in aggregate in an anonymized way. We're compliant with GDPR rules.
Here's our privacy policy for more information: https://www.rescuetime.com/privacy