Does the app use USGA or WHS rules?

The handicap maths follows the World Handicap System (WHS), which the USGA, R&A and most national federations (including the Swedish Golf Federation) jointly use. So whether you call your number a USGA Index or a WHS Index, the conversion to course/playing handicap is the same.

We don't post your scores to your home federation - that's done by your home club's system. Golf with Mates is for tracking the round itself.