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UUID Generator

Processed Client Side

Generate cryptographically-random UUID v4 identifiers in bulk. Uses crypto.randomUUID when available.

Configure
UUID v4 format
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
128 bits · 122 random bits · version 4
Count10
1100
Each UUID v4 is randomly generated using the browser's cryptographic PRNG (crypto.randomUUID). Collision probability is effectively zero.
UUIDs (10)
10 UUIDs
17eb8f197-f590-4947-ade3-eabe420e7bcb
2bf58049b-4070-4376-b88b-1500e0e2916e
3ac2a9576-e1d3-484e-9344-3e04cf8ebb0d
482640f60-a66c-47f1-aece-bf17f8b3bddb
559364675-cedd-4e9a-acaa-d78f3fe20056
6559a3a82-97eb-445d-bc4e-ce52b5b8426f
70ab86fe2-2f3c-43cf-8968-c0d98e85538f
825b652c5-2c78-4fac-9a35-96716f493800
9e096babd-d36c-48e4-922d-11a98e48ba15
10866fde1d-e00a-492d-a5a9-a08b28403ee1

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About UUID Generator

This tool runs entirely in your browser. Whatever you paste is processed on your own device and is never uploaded, logged, or sent to any server.

Generate version 4 UUIDs in bulk — random 128-bit identifiers formatted as the familiar 8-4-4-4-12 hexadecimal string. Randomness comes from the browser cryptographic random number generator, not from Math.random, so the values are suitable for real database keys and not just for test fixtures. Generate as many as you need in one pass, switch the output to uppercase for systems that expect it, and copy a single UUID or the whole batch at once. A v4 UUID has 122 random bits, which means you can generate billions of them without a realistic chance of a collision — which is exactly why they are used to create identifiers without a central coordinator.

Key features

  • Version 4 UUIDs generated with the cryptographic random source, via crypto.randomUUID where available
  • Bulk generation — produce a whole batch in one click instead of one at a time
  • Uppercase toggle for systems and databases that expect uppercase hex
  • Copy any individual UUID, or copy the entire batch as a newline-separated list
  • Correctly sets the version and variant bits, so every value is a standards-conformant v4
  • Regenerate instantly for a fresh batch
  • Runs entirely in your browser — no server ever sees the identifiers you generate

How to use it

  1. Set how many UUIDs you want.
  2. Click Generate.
  3. Turn on UPPERCASE if your target system expects uppercase hexadecimal.
  4. Copy one value with its row button, or use Copy all for the whole batch.

Tips & common mistakes

  • Version 4 is random. If you need identifiers that sort chronologically, look at UUID v7 or ULID instead — v4 keys scatter across a B-tree index and can hurt insert performance on large tables.
  • Store UUIDs as a native uuid column in PostgreSQL or BINARY(16) in MySQL rather than as a 36-character string — it is roughly half the storage and materially faster to index.
  • Collisions are not a practical concern: with 122 random bits you would need to generate billions per second for years before the probability became meaningful.
  • UUIDs are unguessable but not secret. They are fine as identifiers in a URL, but they are not an access control mechanism on their own.
  • Case does not affect identity — the standard says hex digits are case-insensitive — but string comparison in your code does. Normalise to one case before comparing.
  • The version digit is always 4 and the variant digit is 8, 9, a, or b in a valid v4. If those positions look different, the value came from a different UUID version.

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Frequently asked questions

10

Click "Generate" and a new UUID v4 is created instantly using your browser's cryptographic random number generator. Use the count slider to generate up to 100 at a time.

UUID v4 — randomly generated using the browser's crypto.randomUUID API when available, with a fallback to crypto.getRandomValues for older browsers.

UUID v4 has 122 bits of randomness. The probability of generating two identical UUIDs is approximately 1 in 5.3 × 10 to the power of 36 — effectively impossible in practice.

They are the same thing. GUID (Globally Unique Identifier) is Microsoft's name for what the RFC standard calls UUID (Universally Unique Identifier). The format is identical.

Up to 100 at a time using the count slider. All generated UUIDs can be copied to your clipboard at once with the "Copy all" button.

It works, but random v4 keys scatter across a B-tree index and can slow inserts on large tables. If you need identifiers that sort chronologically, consider UUID v7 or ULID instead.

Use a native uuid column in PostgreSQL or BINARY(16) in MySQL rather than a 36-character string. That is roughly half the storage and materially faster to index.

Not for identity — the standard treats hex digits as case-insensitive. It does matter for string comparison in your code, so normalise to one case before comparing.

No. They are unguessable, which makes them fine as identifiers in a URL, but they are not an access control mechanism. Anyone who obtains the UUID has whatever it unlocks.

The first digit of the third group is the version, always 4 here, and the first digit of the fourth group is the variant, which is 8, 9, a, or b. Different values mean a different UUID version.