Generate cryptographically secure UUID v4 identifiers instantly
8424a5eb-68cb-47c0-a723-b667a9aa9206 c47a7704-0c94-4b42-a59f-0817f030ae33 8942428d-30be-4971-aea7-4a962b33373f b5232ae1-9361-436d-a737-e84544b13cff 256c7989-eeb3-464f-8716-0b41c751edb5
Generated using crypto.getRandomValues() — cryptographically secure, 122 bits of randomness.
The UUID Generator creates version 4 (random) UUIDs on demand, producing standard 36-character identifiers in the canonical 8-4-4-4-12 hyphenated format such as f47ac10b-58cc-4372-a567-0e02b2c3d479. Every UUID is generated locally in your browser using the platform's cryptographic random number generator, so you get RFC 4122 / RFC 9562 compliant identifiers without hitting any server.
Developers reach for this tool when they need unique primary keys, correlation IDs for distributed tracing, idempotency keys for API requests, test fixtures, or unique filenames. Because v4 UUIDs are generated independently on any machine without coordination, they are ideal for databases, microservices, message queues, and offline-first apps that must assign IDs before syncing.
A UUID (Universally Unique Identifier) is a 128-bit value written as 32 hexadecimal digits split into five groups: 8-4-4-4-12. A version 4 UUID fills nearly all of those bits with random data, then fixes two positions to mark the variant and version. The 13th hex digit is always 4 (the version), and the 17th digit is always one of 8, 9, a, or b (the RFC 4122 variant). That leaves 122 random bits.
Those 122 random bits mean there are 2^122 possible v4 UUIDs, roughly 5.3 x 10^36. The collision probability is so low that you would need to generate about 2.71 x 10^18 UUIDs before there is even a one-in-a-billion chance of a single duplicate, which is why v4 UUIDs are treated as effectively unique without a central authority. This tool sources randomness from the browser's crypto.getRandomValues (via crypto.randomUUID where available), a cryptographically strong generator, rather than Math.random.
Note that v4 UUIDs are random, not sortable. If you need time-ordered identifiers for database index locality, look at UUID v7 or ULIDs; v4 is the right choice when you simply want an unpredictable, unique value.
Yes, it is completely free with no sign-up. UUIDs are generated entirely in your browser using JavaScript, so nothing is sent to a server and no identifiers are logged or stored anywhere.
It generates version 4 (random) UUIDs, which are the most commonly used type. They are marked by the digit 4 in the version position and use 122 random bits.
In practice, no. With 2^122 possibilities the chance of a collision is astronomically small, so v4 UUIDs are safe to use as unique keys without checking for duplicates in most applications.
It is generated with a cryptographically secure random source, but a UUID is only 122 bits of entropy and its structure is public. It is fine for session or correlation IDs, but for high-security secrets use a dedicated random token or key of appropriate length.
If the tool exposes a count field, you can produce a batch in a single click, which is handy for seeding test databases or generating fixtures. Otherwise, click Generate repeatedly to create as many as you need.
UUIDs are output in lowercase by convention, but they are case-insensitive per the spec. Most systems accept either case, though it is best to store them consistently to avoid mismatched comparisons.
The canonical form includes four hyphens, and many parsers expect them. Some storage layers strip hyphens to save space; if you remove them, make sure the same convention is used everywhere you read and write the value.