Trading cards drop while you idle, then sell on the Steam Community Market for real wallet funds. Most idlers just farm whatever game is first in your list. Our Card Farmer is smarter: it looks up the live market value of the cards each of your games still has to give, then farms the most valuable ones first so your time turns into the most money.
It runs one game at a time on purpose - that's the only way Steam actually drops cards - and moves on the moment a game runs dry. It also skips games that can't drop cards for you (free-to-play titles you haven't spent on, or accounts under Steam's $5 limit) instead of wasting hours on them, and messages you when a batch finishes.
Included on every paid plan (Starter, Pro, and Lifetime).