What a "cracked" Minecraft server actually is

Every time you join a normal Minecraft server, the server asks Mojang whether the account you claim to own is really yours. That check is called online mode, and it is on by default. A cracked server has turned it off.

The practical effect is that anyone can connect with any username, whether or not they bought the game. That is the whole appeal, and also the whole problem.

What turning the check off costs

• Usernames stop being proof of identity. Nothing stops someone connecting as your name, which is why cracked servers lean on password plugins — you log in with /login every session.
• Skins break. Without Mojang in the loop the server cannot fetch your skin, so cracked servers run their own skin systems or you turn up as Steve.
• Bans are weaker. A ban attached to a username is defeated by typing a different username, so moderation leans on IP bans, which catch the wrong people.

Cracked is not the same as pirated. Running a server in offline mode is a legitimate configuration Mojang ships; how the people joining it obtained the game is a separate question, and one this directory takes no view on.

Is a cracked server worse?

Not inherently. Offline mode is common on servers built for regions where paying in a foreign currency is genuinely hard, and plenty of them are large, well-run and long-lived. What you are trading away is identity: your account is only as safe as the password plugin protecting it, so use a password you do not use anywhere else.

One thing worth knowing about this directory specifically: a status ping cannot tell you whether a server runs offline mode. Nothing in the protocol reports it. Listings only carry an account mode when the owner states it, which is why you will see it blank on servers we pinged rather than servers that were submitted.