UUID Generator
Click Generate to produce a fresh UUID v4 instantly, or set a quantity (up to 50) to generate a batch. Each UUID is cryptographically random, produced using your browser's crypto.randomUUID() or crypto.getRandomValues() API. Copy all results with one click — nothing is sent to a server.
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Developer & WebAbout the UUID Generator
A UUID (Universally Unique Identifier) is a 128-bit value formatted as five hyphen-separated groups of hexadecimal digits: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" in the third group marks it as version 4 (random), and the "y" encodes the RFC 4122 variant bits (8, 9, a, or b). Version 4 UUIDs are the most widely used type because they require no coordination between generators — the probability of a collision in a set of 1 trillion UUIDs is approximately 0.000000001%, making them effectively unique in practice. Developers use UUIDs as primary keys in distributed databases (PostgreSQL, MongoDB), as idempotency keys in payment APIs, as correlation IDs for distributed tracing (OpenTelemetry), and as file or asset identifiers in storage systems like AWS S3. This tool uses the browser's native crypto.randomUUID() where available, falling back to crypto.getRandomValues() for older environments — both produce cryptographically strong randomness, unlike Math.random().
What is a UUID v4?▾
UUID v4 is a 128-bit identifier generated from cryptographically random bytes. It follows the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where "4" denotes version 4 and "y" encodes variant bits. Collisions are astronomically unlikely.
Is it safe to use as a database primary key?▾
Yes — UUID v4 is widely used as a primary key in relational and NoSQL databases. For write-heavy tables in PostgreSQL, consider UUID v7 (time-ordered) to avoid index fragmentation, but v4 is fine for most use cases.
Why not use Math.random() to generate UUIDs?▾
Math.random() is not cryptographically secure and can produce predictable values. This tool uses the browser's crypto.randomUUID() or crypto.getRandomValues() API, which is cryptographically strong and suitable for security-sensitive identifiers.