Muster records time on your phone as you work, applies your employer's overtime rules, and fills in the timesheet they gave you — so the claim you submit matches the days you had.
Clock in, log a standard day, or add an entry by hand. Travel, overnight stays, mileage and breaks are part of the entry rather than an afterthought at the end of the month.
A weekly threshold, what each hour above it is worth, Sundays, bank holidays, rest days, travel time. Stated once for the employer, with a per-person exception where someone's contract differs.
The timesheet your employer issued, filled in — not a generic export they have to re-key. The figures are shown with their arithmetic so you can check them before you send.
Days with nothing recorded, days with no break, work with no country against it. Flagged before you submit rather than queried afterwards.
An estimate from your own logged hours, gross, before tax — not a payroll record, and never presented as one.
Muster was built for one engineer whose overtime was worked out by hand every month, against an employer's spreadsheet with no rules written in it. The rules had to be reconstructed, and then stated somewhere they could be checked.
That is still the shape of it: the rules are visible, and they say where they came from — the shipped defaults, the employer's agreement, or an exception on one contract.
It runs a real timesheet for real pay, every month. It is not a product with a support desk. Accounts are set up by hand, one at a time.