The cards are distributed according to the 'mastery level' and colored according to the 'date of the last mastery' they become darker over time. Thich system allows you to distinguish easy cards from difficult ones immediately, and simultaneously see which cards must be refreshed because they have not been reviewed for a long time.

Stackz supports any other unicode lanugage of the Windows operating system as well. The constantly growing online wordlist archive currently contains over 200 wordlists for Japanese, Chinese, Korean or Thai.

The Standard edition does not include Japanese and Chinese dictionary tools.