UUID generator.
Random v4, sortable v7, GUID style or a short NanoID. One or a thousand, made with your browser's crypto.
- Free
- No signup
- Runs in your browser
Fully random. The default almost everywhere, and what crypto.randomUUID() returns.
Made in your browser with crypto.getRandomValues. Nothing is stored or sent.
How it works.
- 1
Pick UUID v4, UUID v7 or NanoID, and how many you need.
- 2
Set the format: uppercase, braces or no hyphens, or the NanoID length and characters.
- 3
Copy one or all of them. Generate again for a fresh batch.
v4 or v7?
A v4 UUID is 122 random bits. A v7 UUID, defined in RFC 9562, starts with the current time in milliseconds and fills the rest with random bits, so ids made later sort later.
That ordering matters for database keys. New v7 rows land at the end of a B-tree index instead of on random pages, which keeps inserts fast as a table grows. Use v7 for primary keys and v4 when an id shouldn't reveal when it was made.
UUID, GUID and NanoID
GUID is Microsoft's name for the same 128-bit format, often written uppercase inside braces. Switch both on above and you have one.
NanoID is a shorter string id. Its default of 21 characters from a 64-character alphabet carries 126 random bits, a little more than a v4 UUID, in 15 fewer characters.
Questions, answered.
What is a UUID?
A 128-bit identifier written as 36 characters, like 0f8fad5b-d9cb-469f-a165-70867728950e. Any machine can make one without asking a central server, and in practice they never repeat.
Can two UUIDs ever be the same?
In theory, yes. In practice, you would need about 2.7 quintillion v4 UUIDs before the odds of a single duplicate reach 50%. A bug in your random source is a far bigger risk than chance.
Is a GUID the same as a UUID?
Yes. GUID is the name Microsoft uses for the same format. Windows tools tend to print it uppercase and wrapped in braces, which the switches above reproduce.
How do I generate a UUID in JavaScript?
crypto.randomUUID() works in every modern browser and in Node, and returns a v4 UUID. For v7, use the uuid package from version 10, or Postgres 18's built-in uuidv7() function on the database side.
Should I use UUID v7 as a primary key?
For most apps, yes. It keeps the benefits of a UUID, like ids made on the client and no guessable sequence, while inserting in order like an auto-increment column.
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Ids sorted. Now the app around them.
Let people sign in with Google.. Add API keys my users can create and revoke.. Send a welcome email right after signup.Hype Stack is a free starter with Postgres, Prisma and Kysely already set up behind one Hono API, so your agent goes straight to the tables that are yours.