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How to generate a UUID

You need a unique id for a record, a test fixture or an API key placeholder. You will generate one or many random UUIDs in this tab and copy them. A version 4 UUID looks like 3f2504e0-4f89-41d3-9a0c-0305e82c3301. Nothing leaves this tab.

6-minute read

Today's result A list of random version 4 UUIDs, with or without hyphens, in lower or upper case, ready to copy.

Open the UUID generator when you need ids. The values are random and never stored; generate again for a fresh set. Nothing is uploaded.

Open UUID generator
Contents

  1. Know what a UUID v4 is

    36 characters: 32 hex digits in groups of 8-4-4-4-12. The third group starts with 4 (version) and the fourth with 8, 9, a or b (variant). The other 122 bits are random, so collisions are not a practical concern.

    8-4-4-4-12 hex groups; the third group starts with 4, the fourth with 8, 9, a or b.
    8-4-4-4-12 hex groups; the third group starts with 4, the fourth with 8, 9, a or b.

  2. Open UUID generator on cv.cm

    Five UUIDs with hyphens in lower case are ready; the list refreshes as you change the options. Nothing is uploaded.

    Open UUID generator

  3. Set how many

    Drag the How many slider from 1 to 20. The list updates at once, one UUID per line; press Generate for a fresh set with the same settings.

  4. Choose hyphens and case

    Untick Hyphens for a 32-character form some databases and file names want. Tick Uppercase if a schema or Windows registry key expects capitals. Both forms are the same UUID.

    Hyphens off gives 32 characters; Uppercase gives capitals; both name the same UUID.
    Hyphens off gives 32 characters; Uppercase gives capitals; both name the same UUID.

  5. Copy the list

    Copy list puts every UUID on the clipboard, one per line, for a SQL insert, a fixture file or a spreadsheet column.

  6. Use the right version

    v4 is random and right for most ids. If you need ids that sort by time, use UUID v7 or a ULID from your database or language instead.

Use with these tools

FAQ

Can I generate a UUID free online?

Yes. cv.cm makes them in this tab with Web Crypto. Nothing is uploaded or stored.

Which version is it?

Version 4, random. The third group starts with 4.

Can two UUIDs collide?

In practice, no: 122 random bits give about 5.3 × 10^36 values.

Can I get them without hyphens?

Yes. Untick Hyphens for the 32-character form.

Are the UUIDs saved anywhere?

No. They exist only in this tab until you copy them.