I also felt features like goals, invoices and management of clients shouldn't require premium subscription. And for the most part, I feel I'm right. Especially after implementing these features.
The website is now in beta testing and I'd love your feedback on some of the metrics you'd like to see that are not currently on the wakatime website.
I've already added stats about the amount of coding time spent writing code. And for me it feels like a big deal thus far.
I've also been playing with an idea of showing developer focus/attention as buckets of heartbeats over time or heartbeat frequency over time.
I feel there is more. Looking forward to hearing your feedback