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Generate UUID v4 identifiers instantly. Create single or bulk UUIDs with one-click copy for your projects.
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A UUID (Universally Unique Identifier) is a 128-bit value designed to be globally unique without requiring a central authority. UUID version 4, which this tool generates, uses cryptographically secure random numbers to produce identifiers with an astronomically low probability of collision — you would need to generate roughly 2.71 quintillion UUIDs before having a 50% chance of a single duplicate.
UUIDs are the standard choice for database primary keys in distributed systems, API resource identifiers, session tokens, correlation IDs for distributed tracing, and idempotency keys for payment processing. Unlike auto-incrementing integers, UUIDs can be generated on any client or server independently and merged later without conflicts.
The standard UUID v4 format is a 36-character string with hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" indicates the version, and the "y" character is constrained to 8, 9, a, or b to indicate the variant. This tool generates UUIDs using your browser's cryptographically secure random number generator (crypto.randomUUID or crypto.getRandomValues).