From Minecraft Wiki
Official Minecraft demo releases available to try for free include:
- A Minecraft demo mode of the current game version for users who have not purchased the game yet and would like to try it out first. You can play on a world for up to 100 minutes.
- Minecraft Xbox edition has a free trial version available to download from XBLA. However, you can only play the tutorial world.
- The PC Gamer Minecraft Demo (outdated) - a limited version of Minecraft Beta 1.3. You can play on a world for up to 100 minutes.
- Minecraft Classic (outdated) - the first development version of Minecraft available in both Singleplayer and Multiplayer.
- Minecraft 4k (created separately from Minecraft) - a very limited version of Minecraft developed for the Java 4K in less than 4 kilobytes.