So you want minecraft for free. By all means check out this link.
Free Minecraft

Free Version
This Minecraft version requires no premium account and has all three single-player modes: Survival, Hardcore and Creative. It also receives updates, allows username changes, and supports multiplayer on unofficial or “cracked” servers. Click here to download the free Minecraft version, or here to play from your browser (single-player).

If you are concerned about playing Minecraft for free, relax. The game’s original developer, Notch, suggested a different way to play the game. This is great news, especially for players who can’t afford a premium account just yet.

The first thing you want to do is download the free version, which is the simplest, no cost method to play the latest version both offline and online.