UUID Generator

How to use

Select the UUID version — V4 (random) is the most common choice for unique identifiers. Enter how many UUIDs to generate (1–100) and choose your preferred format: standard lowercase with hyphens (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx), uppercase, or without hyphens. Click Generate to create the batch. Click Copy All to copy every UUID to clipboard at once, or copy individual UUIDs one by one. The generator runs entirely in your browser using cryptographically secure randomness from the Web Crypto API.

Why use this tool

UUIDs are the standard way to generate unique identifiers for database records, API resources, distributed systems, and session tokens without requiring a central ID server. UUID v4 uses 122 bits of randomness, making collisions statistically impossible for practical purposes. Use this generator when building applications that need unique IDs across multiple databases or services, generating test data, or creating unique filenames. The Web Crypto API ensures the randomness is cryptographically strong, unlike Math.random() which should never be used for unique IDs in production.

FAQ

Are generated UUIDs truly random?

Yes. The tool uses crypto.randomUUID() — a cryptographically secure PRNG built into modern browsers.

What is the difference between UUID formats?

Hyphenated (8-4-4-4-12) is the standard. Compact removes dashes. Braces add {} around it. URN prefixes with 'urn:uuid:'.

Are UUIDs sent to your servers?

No. All generation happens in your browser. Nothing is ever transmitted.

What is UUID v4?

UUID v4 is a randomly generated unique identifier. It uses 122 bits of cryptographic randomness, producing 5.3×10^36 possible values. The collision probability for generating 1 billion UUIDs per second for 86 years is less than 50%.

Is UUID truly unique?

For practical purposes, yes. UUID v4 has 2^122 possible values (~5.3×10^36). Generating 1 billion UUIDs per second, you would need to run for 86 years to have a 50% chance of a single collision — effectively impossible in any real application.

UUID vs nanoid vs ULID — which should I use?

UUID v4 is the most widely supported standard. nanoid is shorter and URL-safe. ULID is sortable (timestamp prefix). Use UUID v4 for maximum compatibility, nanoid for short IDs in URLs, ULID when you need time-ordered IDs.