Daysabroad
Why it exists. I nomad a lot and I am careful about visa limits. Counting Schengen days by hand in a spreadsheet is exactly the kind of arithmetic you get wrong once and regret for years.
An iPhone app that tracks which country you are in and counts the days against whatever rules you care about — Schengen 90/180, a per-entry visa, a residence permit, a 183-day tax threshold. It runs in the background and you are meant to forget it is there; the number is simply correct when someone asks for it.
There are no servers. Your history stays on your phone and in your own iCloud.