Finishes: Colors & Stains

Since PokerTracker software doesn't fit into either of these categories it is generally allowed on most sites, including industry leader PokerStars.

This is done to let to analyze your own game performance by revisiting your game stats. But you are not allowed to use such software while you are playing on PokerStars. To sum it all up, the answer to the question Does PokerStars allow HUD?  is, yes.