I tried many task managers and love Doit.Im. It is undoubtedly the best one: it is simple and minimalistic, yet powerful.

The only thing it lacks a proper API to bridge it with other services. For example, there is a habit-gamification project Habitica, where you get rewards every time you finish task (or get punished when tasks are not finished). But there is no way to connect it with Doit.Im: existing api can only add tasks, and that is not enough. Other option would be to connect with IFTTT receipts, but it is not available yet.

So, please, invest some time and make Doit.Im even better and awesome: let it be connected with other apps and services. I believe it will be a big benefit and allow more users join and enjoy this app.