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UUID Generator

Generate version 7 or version 4 UUIDs in bulk, and check the version and time of any UUID.

By Nitin Raturi · Last reviewed

Input

How to use the UUID Generator

Make random or time-ordered UUIDs, or check one you already have.

  1. Choose version 7 (time-ordered) or version 4 (random).
  2. Choose how many and the format.
  3. Copy the list, or press Generate again for new ones.
  4. Paste a UUID under “Check a UUID” to read its version and time.

Good to know

  • Nothing is stored or sent; new UUIDs are made each time the page loads.
  • Tap the ⓘ next to any field for a short guide to it.

RFC 9562 UUIDs from your browser’s secure random number generator.

Runs in your browser. Nothing you type is uploaded or saved in the link.

UUID version

Version 7 starts with the time, so new IDs sort in creation order. Version 4 is fully random.

How to fill it in

  • Use version 7 for database keys and logs. Use version 4 when IDs should reveal nothing, not even time.

How many

How many UUIDs to make at once.

How to fill it in

  • Choose 1 to 1,000. They are made on your device with secure randomness.

Format

How the UUID is written. The value is the same in every format.

How to fill it in

  • Lowercase with hyphens is the standard form. Some systems want capitals, braces or no hyphens.

Check a UUID

Paste any UUID to see its version, variant and, for time-based versions, when it was made.

How to fill it in

  • Hyphens, braces and “urn:uuid:” are all accepted.

Example

The RFC 9562 sample 017f22e2-79b0-7cc3-98c4-dc0c0c07398f is version 7, made at 2022-02-22T19:22:22Z.

Result

5 UUIDs, version 7

—

Checked UUID

Version
7
Variant
RFC 9562
Made at (UTC)
2022-02-22T19:22:22Z
Made at (IST)
Wed, 23 Feb 2022, 00:52:22 IST
Standard form
017f22e2-79b0-7cc3-98c4-dc0c0c07398f

ChangelogHow we test this toolEmbed this tool

How this calculator works

  1. Step 1Start with the time48 bitsMilliseconds since 1970, so newer IDs sort later.
  2. Step 2Add randomness74 bitsFrom your browser’s secure random generator.
  3. Step 3Mark the version4 + 2 bitsThe version digit and the variant bits.

A UUID is a 128-bit identifier that systems can create on their own without asking a central server, with a vanishingly small chance of two being the same.

Worked example: the RFC 9562 sample

017f22e2-79b0-7cc3-98c4-dc0c0c07398f was made at 2022-02-22T19:22:22Z: the time is written in its first 12 hex digits.

Reading 017f22e2-79b0-7cc3-98c4-dc0c0c07398f
Layout
tttttttt-tttt-7rrr-Vrrr-rrrrrrrrrrrr
  1. First 12 hex digits017f22e279b0
  2. As milliseconds1645557742000
  3. Version digit (13th)7
  4. VariantRFC 9562
  5. Made at2022-02-22T19:22:22Z

Reading the result

  • Version 7Time-orderedSorts by creation time, which keeps database indexes compact.
  • Version 4Fully randomReveals nothing about when it was made.
  • Secure randomnessMade with crypto.getRandomValues on your device.
  • Not a secretUUIDs are identifiers, not passwords or tokens.
  • v7 reveals timeAnyone can read when a version 7 UUID was made.
  • Never storedNew UUIDs each time; nothing is saved or sent.

A UUID is a unique identifier, not a secret. Passwords and hashes serve different purposes.

For a secret, use the password generator. The hash generator fingerprints data, and the Unix timestamp converter reads millisecond timestamps like the one in a version 7 UUID.

Common mistakes

  • Mistake: Using a UUID as a password-reset or session token.

    Instead: Use a dedicated secret token from a security library.

  • Mistake: Using version 7 where the creation time is private.

    Instead: Use version 4 so no time is exposed.

  • Mistake: Comparing UUIDs case-sensitively.

    Instead: Treat upper and lower case as the same value.

Read how we test our calculators, or browse more developer tools.

Frequently asked questions

Should I use UUID version 4 or version 7?

Version 7 begins with the creation time, so new IDs sort in order, which suits database keys. Version 4 is fully random and reveals nothing, not even when it was made.

Can two UUIDs ever be the same?

In practice, no. A version 4 UUID has 122 random bits. You would need to make billions of them before a repeat became even slightly likely.

Are these UUIDs safe to use as passwords or tokens?

No. UUIDs are identifiers. Use a dedicated secret token for sessions or password resets.

Are the UUIDs stored anywhere?

No. They are made in your browser with secure randomness and are new each time. Nothing is sent to a server or saved in the link.

How do I read the time from a UUID?

Paste it under “Check a UUID”. Versions 7, 6 and 1 carry their creation time, which the checker shows in UTC and IST.

Sources and methodology

The formulas are standard time-value-of-money results. We check every figure against golden values worked out independently, by closed form and by month-by-month simulation; see the methodology.

Written and maintained by Nitin Raturi, a software engineer (about the author). Last reviewed 27 Oct 2026; next review due by . Found an error? Tell us.

Changelog

  • : Initial release. Demand metrics remain unverified.

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