If you're looking to download the game from outside Steam for free, here are some general tips:
"The Binding of Isaac: Repentance" is an expansion to the base game and has been well-received. If you're interested in playing it, consider supporting the developers by purchasing it through official channels. If you're looking to download the game from
If you simply dislike the Steam client, GOG is your best answer. The GOG version: If you're looking to download the game from