About HabitKit.
HabitKit is a habit tracker app for iPhone and Android, and it is made by one person. I am that person. This page exists mostly so that when something on this site cites a study, you can see who is doing the citing.
Who I am
My name is Sebastian Röhl. I am an independent app developer in Germany, I build HabitKit and FocusKit, and I answer the support email for both. There is no team behind that address.
I started making these apps for the same reason people download them. If you want to improve something you have to measure it first, so I began measuring, and the measuring turned into an app.
How long this has been running
The first version of HabitKit reached the App Store in November 2022. The changelog lists its releases, including updates that only fixed something.
As of August 2026 the app holds 4.8 out of 5 from 8,335 ratings on the App Store and 4.7 from 11,493 on Google Play.
Why the grid works the way it does
Every habit in HabitKit is a grid of small squares, one per day, columns for weeks, and the grid extends through the current week. That is close to the whole interface, and it is an argument rather than a decoration.
A streak only describes the current run. It begins at your last gap and knows nothing before it, which is why a habit you have kept for two hundred days with one bad Friday and a habit you started on Friday can both read three. Those are different situations, and they deserve different reactions from you.
The grid is the part that knows the difference. It keeps the whole record on one screen, gaps included, so a missed day reads as one pale square in a year rather than as a counter going back to zero. The streak number is still there, because it does real motivational work. It is just not the only thing on the screen.
What the app does and does not do
HabitKit is free to download on both stores. Your habits live in a database on the phone: there is no account or sign-up, and habit history is stored on your device rather than automatically synced to a HabitKit server. Purchases and crash reporting use third-party services; the privacy policy explains those separately. Everything past that is one optional Pro upgrade, bought per store, and the help center says exactly what it covers.
Where the claims on this site come from
The guides are the part of this site that argues from research, and every essay in them cites what it argues from. I write as the app’s developer, not as a clinician or a behavioural-science researcher. Research summaries distinguish findings from practical suggestions, and a study of progress monitoring is not a trial of HabitKit. The point is to use a study’s own numbers: where a page here mentions the famous 66 days it takes to form a habit, it also says that 66 is the median of 39 people, and that the range around it ran from 18 days to 254.
If something in there is wrong, I would rather be told than keep it.
Getting in touch
Write to sebaroehl@gmail.com or find me at @SebastianRoehl. Feature requests, bug reports and disagreements all go to the same place. The support page carries the postal address and the rest of the detail German law asks for, and the help center answers most of what people write in about before they have to write in.