Generate RFC 4122 version 4 UUIDs with cryptographic randomness. Create one or a batch, with or without hyphens, and copy any with one click.
UUIDs are generated locally in your browser using the Web Crypto API. They never leave your device.
Each UUID is 128 bits of randomness — ~3.4 × 10¹ possible values.
UUIDs (Universally Unique Identifiers) are 128-bit IDs that can be generated anywhere, at any time, without asking a central authority. Version 4 — the one this tool generates — is defined by the RFC 4122 standard and is nothing but randomness plus a few fixed marker bits, which is what makes it so easy to use in distributed systems.
A UUID is a 128-bit identifier usually written as 32 hex digits grouped 8-4-4-4-12, like 550e8400-e29b-41d4-a716-446655440000. Version 4 is the random variant: every bit except a few version and variant markers is pure randomness, so IDs can be generated anywhere without coordination.
Random IDs need no central authority: any machine, on any network, at any time can produce one without checking anyone else. That makes them ideal for distributed systems, database keys and client-side tokens. The trade-off is that a collision is possible in principle, just astronomically unlikely in practice.
Each v4 UUID has 122 random bits — roughly 5.3 × 10^36 possible values. You would need to generate trillions of them per second for centuries before the probability of one collision meaningfully exceeds one percent. For any real-world workload, collisions are effectively impossible.
Yes. It uses the browser's Web Crypto API (crypto.getRandomValues), which draws from the operating system's cryptographic random source — the same source used for TLS keys and secure tokens. It is not a predictable pseudo-random sequence.
No — v4 UUIDs carry no time information, so their order is random. If you need identifiers that sort chronologically, look at time-ordered formats such as UUIDv7 or ULID, which embed a timestamp in the high-order bits.
Need identifiers that sort chronologically? Generate time-ordered IDs with the UUIDv7 Generator, or fill an entire test table in seconds with the Mock Data Generator.
If you just finished with UUID Generator, the natural next steps are Password Generator, Random Number Generator, JSON Formatter & Validator, or browse every tool in Daily Tools.