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UUID Generator
Generate RFC 4122 version 4 Universally Unique Identifiers (UUIDs) using cryptographically secure random numbers. UUID v4 uses 122 random bits (6 fixed bits for version and variant), producing identifiers in the standard 8-4-4-4-12 hexadecimal format (e.g., 550e8400-e29b-41d4-a716-446655440000). The collision probability is approximately 1 in 5.3 x 10^36. All generation is client-side.
Generated UUIDs (1)
6ab439cb-68b3-451a-90be-d91060881729Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier), standardized as RFC 4122 and ISO/IEC 9834-8, is a 128-bit identifier. The canonical format is 32 lowercase hexadecimal digits displayed as 8-4-4-4-12 groups separated by hyphens (total 36 characters). UUIDs are used as database primary keys, distributed system identifiers, file names, and API resource IDs where global uniqueness is needed without a central authority.
What is UUID v4?
UUID v4 is generated using random or pseudo-random numbers. The version is indicated by the 13th hex digit (always "4") and the variant is indicated by the 17th hex digit (always "8", "9", "a", or "b" for RFC 4122). This leaves 122 bits of randomness. UUID v4 is the most commonly used version because it requires no network coordination, MAC address, or timestamp — just a good random source like crypto.getRandomValues().
Are generated UUIDs truly unique?
While not mathematically guaranteed unique, the probability of a collision is extremely low (1 in 2^122). You would need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of one collision.
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How to Use
- 1 Click **Generate** to create a new RFC 4122 UUID v4.
- 2 Use the quantity option to generate multiple UUIDs at once.
- 3 Click **Copy** to copy a single UUID, or **Copy All** for batch results.
- 4 Toggle between uppercase and lowercase formats as needed.