Zerdly

UUID Generator

Generates random version 4 or time-ordered version 7 UUIDs in the browser, and inspects any UUID.

100% FreeRuns in your browserBasic
How to use this calculator

Generate

Version

1 to 10,000.

Inspect a UUID

A valid format does not prove a UUID is unique or yours, and a v4 UUID is not an access token.

Runs entirely in your browser. Your input is not uploaded or stored.

How the method works

Inside a UUID v7
Illustrative method
Inside a UUID v7The 32 hex digits of an example UUID v7 above a 128-bit bar: the first 48 bits are a Unix millisecond timestamp, then 4 version bits holding 7, 12 random bits, 2 variant bits holding binary 10 and 62 random bits.017F22E279B07CC398C4DC0C0C07398F----unix_ts_ms · 48 bitsver = 7rand_a · 12 bitsvar = 10rand_b · 62 bits017F22E279B0 hex = 1,645,557,742,000 ms= 2022-02-22T19:22:22.000Z (creation time is visible)
017F22E2-79B0-7CC3-98C4-DC0C0C07398F: the first 12 hex digits (017F22E279B0) are the Unix time in milliseconds — 1,645,557,742,000 ms, 2022-02-22T19:22:22.000Z. The 13th digit is the version (7); the 17th digit (9 = binary 1001) starts with the variant bits 10. The rest is random. A v7 timestamp reveals roughly when the ID was made.

v4 instead fills everything except the version and variant bits with secure random bits. A UUID's format says nothing about uniqueness or who owns it. Fixed example values for illustration — not your result.

How to use this calculator

  1. Choose version 4 (random) or version 7 (time-ordered), how many (up to 10,000), and uppercase or hyphen options.
  2. Press Generate, then copy all or download TXT, CSV or JSON.
  3. Paste any UUID into the inspector to see its version, variant and — for v7 — its embedded time.

How it works

Both versions use only your browser's crypto.getRandomValues; if that is unavailable, nothing is generated. Version and RFC 9562 variant bits are set exactly.

v7 starts with a 48-bit Unix millisecond timestamp, so IDs sort by creation time; within one millisecond a counter keeps them increasing. That timestamp is readable by anyone.

A valid format does not prove uniqueness or ownership, and a UUID is not an access token.

Worked example

A v4 UUID. e.g. 3f2504e0-4f89-41d3-9a0c-0305e82c3301 — the 4 marks the version and the 9 an RFC variant.

Common mistakes

  • Using v7 where the creation time should stay private.
  • Using a UUID as a password or secret token.
  • Assuming uppercase and lowercase UUIDs are different values (they are the same).

Tips

  • Runs entirely in your browser. Your input is not uploaded or stored.

Frequently asked questions

Are they unique?

v4 UUIDs carry 122 random bits — collisions are astronomically unlikely, though never strictly impossible.

Privacy?

Runs entirely in your browser. Your input is not uploaded or stored.

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Cite this tool

Zerdly. (2026). UUID Generator. Retrieved from https://www.zerdly.com/tools/uuid-generator/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.