Cracked launchers or Cracked clients are unofficial Minecraft launchers that allow players to play the game without purchasing it from Mojang Studios, the game's developer. These launchers bypass Minecraft's usual authentication process, which normally checks whether a player has a valid, paid-for copy of the game.
Cracked launchers allow players to play Minecraft for free, often with access to single-player modes and multiplayer servers that don't require authentication - typically referred to as 'cracked' servers.
However, these cracked launchers come with some downsides. Firstly, they are not endorsed or supported by Mojang Studios. This means they can be unstable, may not work correctly, and will not receive official updates. Secondly, they can present a security risk. Lastly, the use of cracked launchers raises ethical issues, as it is essentially a form of piracy, circumventing the payment that would normally go to the game's developers.