Streak is a Trello Power-Up that allows you to track habits straight on your Trello board.
You check off that you've completed your habit using the calendar on the Trello card, and then you can see at a glance how you're tracking across all your habits with the little badges on the front of the cards.
I initially started off hosting this on Heroku's free plan, but it puts your app to sleep after a little while so I switched over to Github Pages for free hosting.
This is my first Trello Power-Up, and whole process was pretty straightforward - I submitted the Power-Up through a form, they came back with some feedback, and it's been available in Trello's Power-Ups directory for a couple of months now!
Let me know if you have any feature suggestions or questions!