UUID Generator
Generate cryptographically secure v4 UUIDs using the Web Crypto API. 100% client-side — no data leaves your browser.
Generate UUIDs
Each UUID contains 122 bits of cryptographically secure randomness, making collisions virtually impossible.
What is a UUID?
Universally Unique Identifier
A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across space and time. Also known as GUID (Globally Unique Identifier). Defined by RFC 4122.
Version 4 (Random)
UUID v4 uses 122 bits of random data, making the probability of generating a duplicate astronomically small — about 1 in 5.3 x 10^36.
Common Use Cases
Database primary keys, session identifiers, API request IDs, distributed system correlation IDs, file naming, and transaction references.
Format: 8-4-4-4-12
UUIDs follow the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where '4' indicates version 4 and 'y' is one of 8, 9, a, or b (variant bits).
UUID Versions Compared
UUID v1 — Time-based
Based on timestamp and MAC address. Sortable but leaks hardware identity. Not recommended for privacy-sensitive applications.
UUID v4 — Random (This tool)
122 bits of cryptographic randomness. No information leakage. The most widely used version for general-purpose unique identifiers.
UUID v7 — Time-ordered (New)
Combines Unix timestamp with random bits. Sortable by creation time. Better for database indexing than v4. Defined in the new RFC 9562.
ULID — Alternative
Universally Unique Lexicographically Sortable Identifier. 128-bit, Crockford Base32 encoded. Sortable, URL-safe, and monotonically increasing.