UUID Generator

Generate UUIDs (v1, v4, v7, v8) in bulk, with format options and a validator. Cryptographically random by default.

Version
How many
1 UUID
  • ddcf3dbc-1336-4a01-bd68-15c0730ea3e6

01 — Overview

How the UUID Generator works

Generate one UUID or a thousand, in whatever version you need. v4 is fully random (default), v7 is timestamp-sortable, v1 is timestamp-based with a node ID, v8 is custom. Format the output as lowercase, uppercase, Base64, or URN. Includes a validator that decodes a UUID into its parts.

02 — Use cases

When to use the UUID Generator

  1. 01

    Generate a primary key for a quick test row in your database

  2. 02

    Seed a fixture file with a thousand realistic IDs

  3. 03

    Get a timestamp-ordered UUID v7 to use as a sortable identifier

  4. 04

    Validate a UUID you pulled from a log and find out which version it is

03 — Examples

UUID Generator examples

Generate 1 × UUID v4

ex 01

5b1f2a8c-3e9d-4b1c-9f6e-1a2b3c4d5e6f

Random UUID, the default for new identifiers in most systems.

Generate 5 × UUID v7

ex 02

0192f3a1-..., 0192f3a1-..., 0192f3a1-..., 0192f3a1-..., 0192f3a1-...

Timestamp-sortable UUIDs. Newer UUIDs sort after older ones lexicographically.

Validate 5b1f2a8c-3e9d-4b1c-9f6e-1a2b3c4d5e6f

ex 03

Valid, version 4 (random)

Confirms the input is a well-formed UUID v4.

04 — FAQ

UUID — frequently asked questions

What's the difference between UUID v4 and v7?

v4 is 122 bits of randomness — collision-proof but unordered, which causes B-tree index fragmentation in databases. v7 prefixes 48 bits of millisecond timestamp before the random bits, so newer UUIDs sort after older ones. Use v7 when ordering matters.

Are these UUIDs cryptographically secure?

Yes. The tool uses the Web Crypto API (crypto.getRandomValues) for all randomness. That's the same source recommended for security-sensitive use in browsers and Node.js.

What's UUID v8?

v8 is the 'custom' version defined in RFC 9562. It lets you encode application-specific data into the UUID while still being a valid UUID. Most apps don't need v8 — pick v4 or v7 instead.

Should I store UUIDs as text or binary in Postgres?

Postgres has a native uuid type (16 bytes) — use it. It's smaller than text (37 bytes for the canonical form) and faster to index. The Drizzle / Prisma / Kysely uuid types map to it directly.

Can I generate UUIDs that are also valid ULIDs?

Not quite — ULID and UUID have different layouts. But UUID v7 covers the same need (timestamp-sortable IDs) and is far more widely supported.

Why does v1 expose my MAC address?

Historically v1 included the host's MAC address as the 'node' field, which was a privacy issue. Modern implementations (and this tool) randomize the node ID instead. Even so, prefer v4 or v7 for new code.

How many UUIDs can I generate at once?

The UI supports up to 1,000 per generation. Beyond that, hit the API in batches.

05 — Reference

Specs and further reading

The primary sources this tool follows. Where behaviour is defined by a specification, we link the specification rather than a summary of it.

  • RFC 9562: UUIDs

    IETF — The current UUID specification, defining versions 1 through 8 including the sortable v7.

  • RFC 4122: A UUID URN Namespace

    IETF — The original UUID specification, now obsoleted by RFC 9562 but still widely referenced.

  • Crypto.getRandomValues()

    MDN Web Docs — The cryptographically secure randomness source this generator uses.

07 — More

Tools that pair with UUID

Hash Generator

Hash a string with MD5, SHA-1, SHA-256, SHA-512, or bcrypt. Compare two hashes side by side.

Auth/hash

API Key Generator

Strong API keys and secrets with prefix support — sk_test_, pk_live_, or your own. Configurable length and charset, bulk mode.

Auth/api-key

Random Number Generator

Generate random integers or floats in any range. Bulk output, allow-repeats toggle, seeded mode for reproducible runs.

Data/random-number

Last updated .