ARR is MRR times twelve, the yearly value of your recurring revenue at today's run rate.
ARR = MRR × 12
ARR is a run rate, not the revenue of the last twelve months and not a forecast. It answers: if nothing changed from today, what would a year bring?
Some companies count only contracts of a year or longer as ARR. If you report ARR to investors, say which definition you use.
sumwerk shows ARR as MRR × 12 next to the MRR, in the dashboard, the API and the exports.
A restricted, read-only key is all it takes. The first import runs in a few minutes; every number you see opens into the customers and Stripe references behind it.