Minecraft UUID and Skin Lookup

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minecraft whitelist.json uuid generator

Generate a Minecraft whitelist.json from a list of usernames

In the Batch tab, paste the names (one per line), pick the UUID source and the output format, and download the file. Names that do not exist at Mojang are listed separately so you can fix the spelling before using the file.

The file formats and the choice between online and offline UUIDs

The Java server's whitelist.json is a list of objects with two fields: uuid, with dashes, and name. ops.json has the same two fields plus level, from 1 to 4, and bypassesPlayerLimit, true or false. The tool generates both with 2-space indentation, as the server itself writes them. For the whitelist to work, the server needs white-list=true in server.properties; with enforce-whitelist=true, when the whitelist is reloaded anyone not on the list is kicked, including players already online.
The UUID source depends on the server mode. With online-mode=true use the Online source: the tool queries Mojang in batches of 10 names (the most the bulk API accepts), merges the replies, keeps the list order and separates the names that do not exist. With online-mode=false use the Offline source: each UUID is computed locally from the MD5 of OfflinePlayer:name, and there is no lookup at all. Mixing the two is the most common mistake, and the result is a whitelist that looks right and keeps everyone out.
The list accepts names separated by line breaks, commas, semicolons or spaces, removes repeats regardless of case and rejects names that break the rule before any lookup. The limit is 100 names at a time; for larger lists, do it in parts and merge the files. Looked-up UUIDs are cached for a few minutes, and Mojang accepts around 200 requests per 2 minutes per IP, so a list of 100 names uses 10 of those requests.
After generating, put the file in the server folder, replacing the old one, and run /whitelist reload so the server rereads the list without restarting. The same names also come out as CSV (name, UUID with dashes and UUID without dashes), handy for spreadsheets and databases, and as name=UUID text, one line per player. Checking the not-found list saves you from the player who types the whitelist wrong and spends half an hour trying to join.

Checked examples

whitelist.json entry (online)

Input: Notch
Expected output: {"uuid":"069a79f4-44e9-4726-a5be-fca90e38aaf5","name":"Notch"}

Official Mojang UUID, with dashes.

whitelist.json entry (offline)

Input: Notch
Expected output: {"uuid":"b50ad385-829d-3141-a216-7e7d7539ba7f","name":"Notch"}

UUID computed from the name.

ops.json entry

Input: Notch, nível 4
Expected output: {"uuid":"069a79f4-44e9-4726-a5be-fca90e38aaf5","name":"Notch","level":4,"bypassesPlayerLimit":false}

Level 4 is the highest.

CSV row

Input: Notch
Expected output: Notch,069a79f4-44e9-4726-a5be-fca90e38aaf5,069a79f444e94726a5befca90e38aaf5

Header: name,uuid,uuid_no_dashes.

Text line

Input: Notch
Expected output: Notch=069a79f4-44e9-4726-a5be-fca90e38aaf5

One line per player.

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

Why is a name under "not found" if the player exists?

Checking the spelling usually fixes it: lower-case l swapped for capital I, zero instead of O or a stray space. Bedrock-only players also have no Java profile and do not show up.

Do I need to restart the server after replacing the file?

No: /whitelist reload rereads whitelist.json. ops.json, however, is usually read only at startup, so for the operator list restart the server or use /op for each player.

What does the ops.json level mean?

It is the operator permission level, from 1 to 4. Level 4 allows everything, including stopping the server. The tool lets you choose the level; use the lowest one that covers the player's needs.

Next steps

The file formats and the choice between online and offline UUIDs

The Java server's whitelist.json is a list of objects with two fields: uuid, with dashes, and name. ops.json has the same two fields plus level, from 1 to 4, and bypassesPlayerLimit, true or false. The tool generates both with 2-space indentation, as the server itself writes them. For the whitelist to work, the server needs white-list=true in server.properties; with enforce-whitelist=true, when the whitelist is reloaded anyone not on the list is kicked, including players already online.

The UUID source depends on the server mode. With online-mode=true use the Online source: the tool queries Mojang in batches of 10 names (the most the bulk API accepts), merges the replies, keeps the list order and separates the names that do not exist. With online-mode=false use the Offline source: each UUID is computed locally from the MD5 of OfflinePlayer:name, and there is no lookup at all. Mixing the two is the most common mistake, and the result is a whitelist that looks right and keeps everyone out.

The list accepts names separated by line breaks, commas, semicolons or spaces, removes repeats regardless of case and rejects names that break the rule before any lookup. The limit is 100 names at a time; for larger lists, do it in parts and merge the files. Looked-up UUIDs are cached for a few minutes, and Mojang accepts around 200 requests per 2 minutes per IP, so a list of 100 names uses 10 of those requests.

After generating, put the file in the server folder, replacing the old one, and run /whitelist reload so the server rereads the list without restarting. The same names also come out as CSV (name, UUID with dashes and UUID without dashes), handy for spreadsheets and databases, and as name=UUID text, one line per player. Checking the not-found list saves you from the player who types the whitelist wrong and spends half an hour trying to join.

Checked examples

whitelist.json entry (online)

Input: Notch
Expected output: {"uuid":"069a79f4-44e9-4726-a5be-fca90e38aaf5","name":"Notch"}

Official Mojang UUID, with dashes.

whitelist.json entry (offline)

Input: Notch
Expected output: {"uuid":"b50ad385-829d-3141-a216-7e7d7539ba7f","name":"Notch"}

UUID computed from the name.

ops.json entry

Input: Notch, nível 4
Expected output: {"uuid":"069a79f4-44e9-4726-a5be-fca90e38aaf5","name":"Notch","level":4,"bypassesPlayerLimit":false}

Level 4 is the highest.

CSV row

Input: Notch
Expected output: Notch,069a79f4-44e9-4726-a5be-fca90e38aaf5,069a79f444e94726a5befca90e38aaf5

Header: name,uuid,uuid_no_dashes.

Text line

Input: Notch
Expected output: Notch=069a79f4-44e9-4726-a5be-fca90e38aaf5

One line per player.

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

Why is a name under "not found" if the player exists?

Checking the spelling usually fixes it: lower-case l swapped for capital I, zero instead of O or a stray space. Bedrock-only players also have no Java profile and do not show up.

Do I need to restart the server after replacing the file?

No: /whitelist reload rereads whitelist.json. ops.json, however, is usually read only at startup, so for the operator list restart the server or use /op for each player.

What does the ops.json level mean?

It is the operator permission level, from 1 to 4. Level 4 allows everything, including stopping the server. The tool lets you choose the level; use the lowest one that covers the player's needs.