A UUID v4 is a 128-bit unique identifier generated with random bits, except for the 4 version bits (position 13) and 2 variant bits (position 19). The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is 8, 9, a or b.
UUID Generator
Cryptographically secure v4 UUIDs — no Math.random
Universally unique identifier with cryptographic security
A UUID (Universally Unique Identifier) is a standardised 128-bit identifier defined by RFC 9562. The v4 format uses random entropy from the operating system — in the browser via the Web Crypto API — making collisions statistically negligible even at global scale. UUIDs are widely used as database primary keys, session tokens and resource identifiers in REST APIs.
Generate, batch or validate in seconds
- Click "Generate UUID" to obtain a unique v4 UUID. The copy button copies it directly to your clipboard.
- On the "Batch" tab, choose a quantity (1–100) and an export format (TXT or JSON), then click generate and download the file.
- On the "Validate" tab, paste any string to check whether it is a well-formed UUID and see its version and variant.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.