UUID Generator
Generate UUID v4 values instantly. Copy individually or in bulk, customize formatting, and validate existing UUIDs.
Validate a UUID
Paste any UUID to check if it's valid.
What is a UUID Generator?
A UUID (Universally Unique Identifier) generator creates 128-bit identifiers formatted as eight-four-four-four-twelve hexadecimal groups separated by hyphens, for example: 550e8400-e29b-41d4-a716-446655440000. UUIDs are standardised in RFC 4122 and designed to be unique across space and time without a central registry. Version 4 (random) UUIDs use 122 bits of randomness, making collisions statistically negligible even at massive scale. Version 7 UUIDs are time-ordered, making them more efficient as database primary keys.
Common Use Cases
- Generate primary keys for database records without a centralised sequence generator
- Create idempotency keys for API requests to prevent duplicate processing
- Assign unique IDs to distributed system components, sessions, or events
- Track objects across microservices where auto-increment integers would conflict
- Generate unique filenames for uploaded assets in cloud storage
How It Works
Version 4 UUIDs are generated using crypto.randomUUID() (where available) or by filling a typed array with crypto.getRandomValues()and formatting it according to RFC 4122 — setting the version bits to 0100and the variant bits to 10xx. All generation happens in your browser; no UUIDs are logged or stored server-side.
Frequently Asked Questions
How likely is a UUID collision?
Extremely unlikely. With version 4 UUIDs you would need to generate about 2.7 × 10¹⁸ UUIDs before having a 50% chance of a single collision — more than the number of seconds since the Big Bang.
What is the difference between UUID v4 and v7?
UUID v4 is fully random with no time component. UUID v7 embeds a Unix millisecond timestamp in the most significant bits, making UUIDs sort chronologically — which improves database index performance for insert-heavy workloads.
Should I use uppercase or lowercase UUIDs?
The RFC 4122 standard recommends lowercase. Most databases and languages accept both, but lowercase is more common in modern APIs and systems. Be consistent within your application.
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UUID v4: Universally Unique Identifiers are 128-bit values used to uniquely identify resources. Version 4 uses random data, making collisions astronomically unlikely — roughly 1 in 5.3×10³⁶.
Uses the browser's native crypto.randomUUID() API — all generation happens locally, nothing is sent to a server.