UUID Generator — Free Online UUID v4, v1, v7 Generator
Generate cryptographically secure UUIDs — v4 (random), v1 (time-based), v7 (sortable) — in bulk with formatting options.
Frequently Asked Questions
UUID Generation: Unique Identifiers Without Coordination
UUIDs solve a fundamental distributed systems problem: how do you generate unique identifiers across multiple machines, processes, or databases without central coordination? A UUID's 128-bit space is large enough that independent random generation is practically collision-free, enabling offline ID generation in mobile apps, microservices, and distributed databases.
UUID v4 is the most popular variant — 122 random bits ensure uniqueness without embedding any metadata. UUID v7, introduced in RFC 9562, adds a millisecond timestamp prefix that makes UUIDs lexicographically sortable. This property is invaluable for database primary keys where B-tree index performance depends on sequential insertion patterns.
Generated UUIDs use crypto.getRandomValues() — the browser's cryptographically secure random number generator — ensuring the random portions are unpredictable and unguessable, suitable for security-sensitive contexts like session tokens and API keys.