Yes, this is true. I only discovered wakatime a few days ago. The major difference at the moment is wakatime's free plan only includes 1 week of data retention, whereas Koala's plan includes indefinite data retention.
Monetization will happen when we start focussing on teams, managers and invoicing.
Which editor do you use btw? Please try Koala for a week as I'm eager to receive feedback. Which editor do you use btw?