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UUID Generator

One click — 1 to 100 UUIDs, all genuinely random.

Buğra SözeriDeveloper
Updated · Published

A UUID is a 128-bit identifier formatted as five groups of hex digits separated by dashes (e.g. f47ac10b-58cc-4372-a567-0e02b2c3d479). Version 4 UUIDs are generated entirely from random bytes, which gives them a vanishingly small collision probability — about 122 bits of entropyper UUID. You can generate billions of them per second and never see a duplicate in your lifetime. The generator below uses your browser’s crypto.randomUUID(), which on every modern device pulls from a cryptographically secure random source. For when to pick v4 vs v7, see our UUID v4 vs v7 comparison.

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Generated with crypto.randomUUID() — cryptographically strong, RFC 4122 version 4. Different on every refresh.

How to use

  1. Set how many UUIDs you need

    Anywhere from 1 to 100. The default is 5, which is enough for most ad-hoc seeding tasks.

  2. Click Generate

    A fresh batch appears immediately. Each click produces values that have never appeared on this page before.

  3. Copy individually or all at once

    Use a row's copy button for a single UUID, or the copy-all button at the top for newline-separated output ready to paste into SQL, JSON, or a CSV.

Frequently asked questions

What is a UUID v4?
A randomly generated 128-bit identifier following RFC 4122 §4.4. Six bits encode the version (4) and variant (RFC 4122); the remaining 122 bits are random.
Are these really cryptographically random?
Yes — crypto.randomUUID() uses the same CSPRNG as crypto.getRandomValues(). On every modern OS this is seeded from kernel entropy and is suitable for security-sensitive applications.
What's the collision probability?
With 122 bits of randomness, you would need to generate roughly 2.7 × 10^18 UUIDs before there's a 50% chance of any two colliding. At a million UUIDs per second, that's about 85,000 years.
Are there other UUID versions?
Yes — v1 (time + MAC), v3 / v5 (namespace + hash), v6 / v7 / v8 (time-sortable). This tool emits v4 only because it's the most universally appropriate and requires no input.
Why is the output uppercase or lowercase?
Convertitive emits lowercase per RFC 4122 §3 ("output should be lowercase"). Most software accepts either; PostgreSQL and Go normalize to lowercase, .NET and SQL Server commonly default to uppercase.
Is this safe to use for primary keys?
Yes. v4 UUIDs are widely used as primary keys in distributed systems. Be aware they're not time-sortable — if you need timestamp ordering, use v7 (we don't generate those here yet).

About

When to use a UUID

Any time you need a unique identifier without coordinating with a central server. Common cases: database primary keys in distributed systems, message IDs in event streams, idempotency keys for HTTP requests, ephemeral session identifiers.

When not to use

If your identifier is shown to humans, prefer a shorter scheme — UUIDs are unwieldy to read and type. If you need ordering (e.g. timeline ordering), use a time-sortable scheme such as ULID or UUID v7 instead.

Sources & references

Authoritative references behind the math, constants, and tables on this page. Verified by Buğra Sözeri on the dates shown and re-checked at every deploy.