UUID / ULID Generator

About UUID Generator

A UUID (Universally Unique Identifier, also called GUID) is a 128-bit identifier written as 36 characters like 550e8400-e29b-41d4-a716-446655440000. UUIDs can be generated independently on any machine with a negligible chance of collision.

This generator creates UUID v4 (random), UUID v7 (time-ordered, defined in RFC 9562) and ULID in bulk. It also inspects any UUID or ULID to show its version, variant and embedded timestamp.

How to use

  1. Choose a type and how many IDs to generate (up to 1000).
  2. Toggle uppercase or hyphens as needed.
  3. Click an ID to copy it, or Copy All to copy the whole list.
  4. Paste an existing UUID or ULID into the inspector to decode it.

FAQ

UUID v4 or v7 — which should I use?

Use v7 for database primary keys: it starts with a timestamp, so new rows are inserted in order, which keeps B-tree indexes compact. Use v4 when the ID must not reveal when it was created.

What is a ULID?

A 26-character, lexicographically sortable identifier: a 48-bit millisecond timestamp followed by 80 random bits, encoded in Crockford Base32. It is similar in purpose to UUID v7.

Can two generated UUIDs collide?

In practice, no. UUID v4 has 122 random bits; you would need to generate about 2.7 quintillion IDs to have a 50% chance of a single collision.

Are these generated securely?

Yes. Random bits come from crypto.getRandomValues, the browser's cryptographically secure random number generator.