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 2d19e7da-a1c6-4d5c-a294-2d301c1556fa
2 63ede68f-1ef7-4063-92d7-17ce1ca1ffc9
3 eff48c64-8b1c-4536-b412-a85f28c65c27
4 d32f4bdf-5311-4c65-a15b-55f727b1bc03
5 e08eb795-9644-47b7-8e43-3f05c88126c6
6 7f784f8c-eeac-4512-9e09-840106154681
7 8d751af7-06ca-461b-9b1a-f97a4d2421f0
8 bbb24b8e-2d61-4612-b4a3-9a8330153d47
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.