Minecraft UUID and Skin Lookup

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minecraft offline uuid generator

Minecraft offline UUID generator (online-mode=false)

Open the Offline UUID tab, type the name exactly as the player joins and copy the result. Nothing is sent to any server: the computation is local and instant, and works even for names that do not exist at Mojang.

How the server makes up the UUID of someone who joins without logging in

On a server with online-mode=false there is no conversation with Mojang, so there is no official UUID for the player. The server makes one up from the name: it takes the string OfflinePlayer: followed by the name, turns it into UTF-8 bytes and applies Java's UUID.nameUUIDFromBytes. That function computes the MD5 (16 bytes), replaces the 4 version bits with 3 and the 2 variant bits with 10 (RFC 4122). That is why every offline UUID has the digit 3 in the version position and a digit 8, 9, a or b at the start of the fourth group.
The name enters the calculation exactly as typed. Notch and notch are different strings, so they give different UUIDs, and a player who joins once as Steve and once as steve becomes two accounts, each with its own inventory. Names with accents or exotic symbols still produce a UUID, but the server usually refuses them first. The tool warns when the name breaks Mojang's rule (3 to 16 characters among letters, numbers and underscore), although the computation stays valid.
The classic problem shows up when the server changes mode. Player data lives in files named after the UUID, such as world/playerdata/UUID.dat, plus stats and advancements. When online-mode is turned on, the same player gets the official Mojang UUID and the server no longer finds the old file: inventory and progress look erased. The fix is to rename the files from the offline UUID to the online one. This page solves the first half: it gives the offline UUID; the online UUID comes from the Lookup tab.
The computation is deterministic and identical on any machine, so you can check it without touching the server. The tool uses its own MD5, validated against the RFC 1321 vectors, and reproduces the known value for the name Notch. In networks with a proxy in front of several servers, backend and proxy must be in the same mode; if one is offline and the other online, each sees a different UUID for the same person.

Checked examples

The name Notch

Input: Notch
Expected output: b50ad385-829d-3141-a216-7e7d7539ba7f

Version 3 at the 13th digit (the 3 in 3141).

Same word in lower case

Input: notch
Expected output: 42653081-a90e-3475-b3d6-3550cdb43f8e

Case changes everything.

Name with an underscore

Input: jeb_
Expected output: a762f560-4fce-3236-812a-b80efff0b62b

RFC 4122 variant: group 4 starts with 8.

Ten-letter name

Input: Dinnerbone
Expected output: 4d258a81-2358-3084-8166-05b9faccad80

The name length does not change the UUID format.

One-letter name

Input: a
Expected output: 52428a0e-1e30-3cb1-976c-e728b2614047

Works for any name.

Full tool FAQ

How do I find a Minecraft player's UUID from their username?

Type the username in the Lookup tab. The tool asks the Mojang API and shows the UUID with dashes (069a79f4-44e9-4726-a5be-fca90e38aaf5 for Notch), without dashes and as the NBT int array. The lookup is case-insensitive and the result carries the official capitalization. The name must exist today: old names that the player has since changed do not resolve.

Does the UUID change when someone changes their username?

What is the difference between the online UUID and the offline UUID?

How is the offline UUID computed, and does it match the Java server?

What is the [I;a,b,c,d] format and when do I use it?

How do I give a player's head with /give?

How can I tell if a skin is classic (Steve) or slim (Alex)?

Can I download the skin and cape of any player?

How many usernames can I convert at once?

Why does my username not show up, or I get a rate limit error?

Frequently asked questions

Is the offline UUID the same as the Mojang account UUID?

Never. Mojang's is random (version 4) and the offline one is computed from the name (version 3). For Notch they are b50ad385-829d-3141-a216-7e7d7539ba7f and 069a79f4-44e9-4726-a5be-fca90e38aaf5.

Can I use this UUID in the whitelist of an offline server?

Yes, and it is what the server expects: in offline mode the whitelist compares against the offline UUID. Use the Batch tab with the Offline source to generate the whole whitelist.json.

Does this work for Bedrock Edition?

No. The OfflinePlayer rule described here is the Java server's. Bedrock identifies players differently, and this tool does not compute those identifiers.

Next steps

How the server makes up the UUID of someone who joins without logging in

On a server with online-mode=false there is no conversation with Mojang, so there is no official UUID for the player. The server makes one up from the name: it takes the string OfflinePlayer: followed by the name, turns it into UTF-8 bytes and applies Java's UUID.nameUUIDFromBytes. That function computes the MD5 (16 bytes), replaces the 4 version bits with 3 and the 2 variant bits with 10 (RFC 4122). That is why every offline UUID has the digit 3 in the version position and a digit 8, 9, a or b at the start of the fourth group.

The name enters the calculation exactly as typed. Notch and notch are different strings, so they give different UUIDs, and a player who joins once as Steve and once as steve becomes two accounts, each with its own inventory. Names with accents or exotic symbols still produce a UUID, but the server usually refuses them first. The tool warns when the name breaks Mojang's rule (3 to 16 characters among letters, numbers and underscore), although the computation stays valid.

The classic problem shows up when the server changes mode. Player data lives in files named after the UUID, such as world/playerdata/UUID.dat, plus stats and advancements. When online-mode is turned on, the same player gets the official Mojang UUID and the server no longer finds the old file: inventory and progress look erased. The fix is to rename the files from the offline UUID to the online one. This page solves the first half: it gives the offline UUID; the online UUID comes from the Lookup tab.

The computation is deterministic and identical on any machine, so you can check it without touching the server. The tool uses its own MD5, validated against the RFC 1321 vectors, and reproduces the known value for the name Notch. In networks with a proxy in front of several servers, backend and proxy must be in the same mode; if one is offline and the other online, each sees a different UUID for the same person.

Checked examples

The name Notch

Input: Notch
Expected output: b50ad385-829d-3141-a216-7e7d7539ba7f

Version 3 at the 13th digit (the 3 in 3141).

Same word in lower case

Input: notch
Expected output: 42653081-a90e-3475-b3d6-3550cdb43f8e

Case changes everything.

Name with an underscore

Input: jeb_
Expected output: a762f560-4fce-3236-812a-b80efff0b62b

RFC 4122 variant: group 4 starts with 8.

Ten-letter name

Input: Dinnerbone
Expected output: 4d258a81-2358-3084-8166-05b9faccad80

The name length does not change the UUID format.

One-letter name

Input: a
Expected output: 52428a0e-1e30-3cb1-976c-e728b2614047

Works for any name.

Full tool FAQ

How do I find a Minecraft player's UUID from their username?

Does the UUID change when someone changes their username?

What is the difference between the online UUID and the offline UUID?

How is the offline UUID computed, and does it match the Java server?

What is the [I;a,b,c,d] format and when do I use it?

How do I give a player's head with /give?

How can I tell if a skin is classic (Steve) or slim (Alex)?

Can I download the skin and cape of any player?

How many usernames can I convert at once?

Why does my username not show up, or I get a rate limit error?

Frequently asked questions

Is the offline UUID the same as the Mojang account UUID?

Never. Mojang's is random (version 4) and the offline one is computed from the name (version 3). For Notch they are b50ad385-829d-3141-a216-7e7d7539ba7f and 069a79f4-44e9-4726-a5be-fca90e38aaf5.

Can I use this UUID in the whitelist of an offline server?

Yes, and it is what the server expects: in offline mode the whitelist compares against the offline UUID. Use the Batch tab with the Offline source to generate the whole whitelist.json.

Does this work for Bedrock Edition?

No. The OfflinePlayer rule described here is the Java server's. Bedrock identifies players differently, and this tool does not compute those identifiers.