UUID Generator

Generate cryptographically random UUIDs in bulk (v4, v7 and nil).

Developer Runs in your browser

v7 sorts by creation time, which is kinder to database indexes.

Generated UUIDs

No UUIDs generated yet

Choose a version and a count, then press Generate. Values come from your browser's cryptographic random source, so nobody else ever sees them.

Inspect a UUID

Checks the format and reads the version, variant and — for v1 and v7 — the embedded timestamp.

Runs entirely in your browser. Your data isn't uploaded — this page makes no network request with anything you type, which you can verify in your browser's network tab. How this works.

What is the UUID Generator?

A UUID is a 128-bit identifier you can generate anywhere without coordinating with a central service and still expect to be unique. That property is why they are everywhere: primary keys, request and trace IDs, idempotency keys, file names, correlation identifiers across services.

This generator uses the browser's cryptographic random number generator, so the values are suitable for real use rather than demos. It produces random v4 UUIDs, time-ordered v7 UUIDs, and the nil UUID, in whatever text format your target system wants.

How to use it

  1. Choose a version: v4 for pure randomness, v7 when you want values that sort by creation time.
  2. Set how many you need — one, or a few thousand.
  3. Pick a format: lowercase, uppercase, braced, or without dashes.
  4. Press Generate, then copy the list or download it as a text file.

Example

Three v7 UUIDs. Note the shared prefix — they sort by creation time.

Input
version: v7, count: 3, format: lowercase
Result
019bdc3f-8a10-7c41-9e2f-31a0d8c4b7e5
019bdc3f-8a11-7d0a-8f61-5c9b2e77a413
019bdc3f-8a11-7f22-b0c4-9de1f2a6c880

Features

  • UUID v4 (random) and v7 (Unix-time ordered)
  • Cryptographically secure randomness via the Web Crypto API
  • Bulk generation with one value per line
  • Lowercase, uppercase, braced and dash-free formats
  • Nil UUID and a validity checker for pasted values

Frequently asked questions

v4 or v7 for database primary keys?
v7 in most cases. Random v4 keys scatter inserts across a B-tree index, which hurts write throughput and cache locality; v7 embeds a millisecond timestamp in the high bits so new rows land together. The trade-off is that v7 reveals creation time.
Could two generated UUIDs collide?
A v4 UUID has 122 random bits. You would need to generate on the order of 10^18 of them before a collision becomes remotely likely — orders of magnitude beyond any real system.
Are these generated on a server?
No. They come from crypto.getRandomValues() in your browser, so no one else ever sees them — including this site.
Is a UUID safe to use as a secret?
A v4 UUID has enough entropy to be unguessable, but treat it carefully: identifiers end up in logs, referrer headers and analytics. Use a purpose-built token for anything security-bearing.
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