UUIDs are 128-bit identifiers — globally unique without a coordination round-trip. Version 4 is the most common variant: 122 bits of randomness plus 6 bits of version and variant metadata, formatted as 36 characters (32 hex plus 4 hyphens). Collisions are astronomically rare for application IDs.
UUID generator
UUID v4 values are random and effectively collision-free for application IDs. Use them for fixtures, request IDs, idempotency keys, and any place a primary key needs to look unique without a server round trip.
UUID v4 generator
Random UUID v4 values for fixtures, IDs, and placeholders. Each call uses crypto.randomUUID() — cryptographically strong, generated in your browser.
How many 8 values
UUIDs
1 0ce976fe-f247-4416-9a3e-322956232a5d
2 02176005-cde1-4ad5-a452-42bdf6b31a6d
3 cf317310-2a20-40a4-9bf2-da1b1d6c4820
4 0e61c184-aab8-454f-95e4-2fb7a2e67744
5 8cd0d19e-78d6-4623-b5d0-5ee6196e50ef
6 b9adf127-3b38-4773-acd0-00b21d633a30
7 1192ed3f-ca0d-4fd0-8cfc-0291adc28655
8 1ddf2bcf-fc6d-4b24-884a-b93ecfcf779c
Common use cases
Primary keys without a database round-trip
Generate client-side, write straight to the row. No SERIAL bottleneck, no insert-and-return-id dance.
Idempotency keys
Stamp each outbound request with a fresh UUID; the server uses it to deduplicate retries safely.
Fixture and seed data
Tests, Storybook stories, and demo seeds all want stable-looking IDs that don’t accidentally collide across runs.
How to use this tool
- 1 Set the batch size (1–50).
- 2 Toggle hyphens or uppercase if your runtime needs a specific format.
- 3 Copy individuals, or copy the whole batch as one newline-delimited block.
- 4 Click Regenerate for a fresh draw.
Frequently asked questions
UUID v4 or v7?
v7 is time-ordered — sortable by creation time, friendlier to indexed databases. v4 is fully random — better when ordering would leak information about user creation patterns.
Are these cryptographically secure?
Yes — crypto.randomUUID() draws from the platform CSPRNG. Don’t use UUID v4 as a security token, though: collision resistance is not the same as unguessability.
What’s a "nil UUID"?
The all-zeros UUID (00000000-0000-0000-0000-000000000000). It’s a sentinel value — useful as "no value yet" in databases that don’t support null primary keys.