Simplistic GitHub-like graph habit tracker. Using for tracking basic living routines that I kept skipping.
The free version is limited in a good way: you can try set up to 4 habits and always archive unused ones. You can mark completion on past days. Daily, Weekly, Monthly.
As improvements recommendation I can suggest to add motivational/encouraging messages. They are a part of reinforcement for habits. You can look at "Repeat" app for iOS as reference. They have more limits, but it positions itself as motivational tool better, also allows to set "times per day"
WinDiary