I have been using ChartedSails, based on a recommendation from an a-cat sailor. Not polars, but pretty spot on race analytics – VMG, "cost" of your maneuvers (time, meters lost). Very easy to upload GPX and give it the info it needs; as of a month ago, it guesses where the start line, upwind, downwind marks are (and lets you adjust, but the guesses are pretty good).
4 short races (click on the race names along the bottom, it'll expand the race and show per-leg analytics) . The 3rd race was the best I think, in a day that was a demolition derby. We capsized or pitchpoled 4+ times over the whole 4 race series, and still managed to come in 2nd.