Tools
Offline player UUID calculator
On a server with online-mode=false players have no UUID from Mojang: the server derives it from the name. Enter a name and get the same UUID the server will assign, in three formats.
Offline UUID
Enter a name — the UUID appears here.
Why you need the offline UUID
The server keeps players by UUID: inventory and position in world/playerdata/<UUID>.dat (world/players/data/ since 26.1), permissions, bans and plugin data by UUID as well. In offline mode the server computes the UUID from the string OfflinePlayer:<name> with MD5 — a version 3 UUID. Change the name and you get a new UUID and an "empty" player.
The calculator helps when you move data around: renaming a player, switching from offline to online mode or back, finding a player's file in the world folder or putting a UUID in a plugin's config. A real Minecraft account has a different UUID — Mojang issues it.
Offline mode without a proxy lets anyone in under any name, including an admin's. If you need it, keep the server behind a proxy that verifies accounts or an auth plugin, and stop cheaters with an anticheat: DGuard works on offline-mode servers and behind Velocity and BungeeCord alike.
Read in the knowledge base
FAQ
How does the server compute a UUID in offline mode?
It takes the MD5 of OfflinePlayer:<name> and makes a version 3 UUID from it, as minecraft.wiki describes. So the same name always gives the same UUID on any offline server.
Does letter case matter?
Yes: Steve and steve give different UUIDs. Enter the name exactly as the player joins with it.
What is the [I;…] format?
The UUID as four 32-bit numbers. That's how NBT and Java Edition commands store it, in entity data for example.
Why does the UUID differ from the one on player profile sites?
Those sites show the UUID of the paid account issued by Mojang. The offline UUID is computed from the name and doesn't match it.
The tools are free. So is anti-cheat protection
DGuard — the best anticheat for a modern Minecraft server — catches all 47 cheat types in our comparison; the nearest rival, Intave, catches 27. Free up to 30 players online, with the same protection as on paid plans.