Are these cryptographically random?

Yes. We use crypto.randomUUID() which the browser implements with cryptographically secure randomness. The IDs are suitable for security-sensitive applications like session tokens, cache keys, and distributed identifiers.

What version is generated?

UUID v4 — the random version. It encodes 122 bits of randomness, with the remaining 6 bits reserved for the version and variant. Collision probability is effectively zero for practical use.

How many UUIDs are safe to generate before a collision?

You'd need to generate roughly 2.71 × 10^18 UUIDs to have a 50% chance of one collision. Even at a million per second, that's about 85 thousand years.

Can I use UUIDs as primary keys in a database?

Yes, but be aware UUID v4 is random, which can degrade B-tree index performance compared to monotonically increasing IDs. Some databases offer UUID v7 or ULIDs to combine randomness with sortable ordering.

Is the page tracking which UUIDs I generated?

No. Generation runs in your browser; we don't see, log, or store any of them.

Files never leave your device

UUID Generator

Generate v4 UUIDs in bulk using the browser crypto API.

How many?

How to use UUID Generator

Choose how many UUIDs you need (1–100).
Click "Generate" — IDs appear instantly.
Copy a single UUID with the inline button, or copy them all as a list.

What's a UUID?

A Universally Unique Identifier is a 128-bit number, usually written in hex with dashes: 550e8400-e29b-41d4-a716-446655440000. The format is standardised so any system in the world can generate IDs without coordination, with negligible chance of collision.

When to use them

Use UUIDs for any identifier that should be unique across services without a central allocator: session IDs, client-generated IDs that may sync later, idempotency keys, and primary keys in distributed databases. For public-facing identifiers, prefer UUIDs to incrementing integers — sequential IDs leak information about your rate of growth and create attack vectors via enumeration.