🆔 UUID Generator
Generate version-4 UUIDs in bulk. Free, unlimited, private — works entirely in your browser.
How to use
- Choose the UUID version — v4 (random) is the right choice for almost everyone.
- Set how many UUIDs you need: one for a single ID, or bulk-generate hundreds at once.
- Click Generate — your UUIDs appear instantly, formatted with hyphens.
- Copy a single UUID, copy all, or download the full list as a text file.
FAQ
Is it really free?
Yes — every tool on this site is 100% free with no limits, no signup and no watermarks.
Is my data private?
Absolutely. All processing happens locally in your browser. Your files are never uploaded to any server.
What is a UUID?
A Universally Unique Identifier: a 128-bit value written as 32 hexadecimal digits in five groups, like 550e8400-e29b-41d4-a716-446655440000. It is designed to be unique without needing a central registry to hand out IDs.
Should I use UUID v1 or v4?
Use v4 (random) unless you have a specific reason not to. v1 embeds a timestamp and your device's MAC address, which leaks information; v4 is purely random, private, and the most widely used version.
Can two UUIDs ever collide?
Theoretically yes, practically never. v4 has 122 random bits — you would need to generate about a billion UUIDs per second for 100 years to reach even a 50% chance of one collision.
Are generated UUIDs safe as database primary keys?
Yes — that is one of their main uses, especially when merging data from multiple sources. One caveat: random UUIDs can fragment indexes in some databases, so high-write systems sometimes prefer time-ordered variants (v7).
Complete Guide to UUIDs
Every distributed system faces the same problem: how do independent computers create IDs that never clash, without phoning home to a central authority? The UUID (Universally Unique Identifier) is the industry-standard answer — a 128-bit number, usually shown as 32 hex digits in five hyphenated groups, with enough randomness that collisions are effectively impossible.
The versions
- v1 — timestamp + MAC: unique and sortable, but embeds your hardware address. Largely legacy now due to privacy concerns.
- v4 — random: 122 bits of cryptographic randomness. The default choice for IDs, tokens, and keys.
- v3/v5 — name-based: deterministic — the same namespace plus name always yields the same UUID. Great for generating stable IDs from existing data.
- v7 — time-ordered: the modern favorite: timestamp-prefixed for database-friendly sorting plus randomness for uniqueness.
Where UUIDs shine
Database primary keys in distributed systems — two servers can insert rows independently and merge later with zero conflicts. Session tokens and API keys — unguessable by design. File and asset naming — user uploads named by UUID can never overwrite each other. They also beat auto-incrementing integers for anything public: sequential IDs leak how many users or orders you have and invite enumeration attacks.
Generation quality matters: UUIDs are only as unique as their randomness source. This tool uses the browser's cryptographic RNG (crypto.getRandomValues) — the same primitive behind TLS — never the predictable Math.random(). Bulk-generate with confidence, and download the list when you need IDs for seeding a database or test suite.
UUIDs vs auto-increment IDs
Traditional databases hand out IDs 1, 2, 3... - simple, but with real drawbacks. Sequential IDs reveal business metrics, enable enumeration attacks by guessing neighboring IDs, and collide horribly when merging two databases. UUIDs solve all three: they are opaque, unguessable, and globally unique, so distributed systems, offline-first apps, and multi-region databases can all generate IDs independently.
Formatting variants you may meet
- Hyphenated: 550e8400-e29b-41d4-a716-446655440000 - the canonical text form.
- Compact: 550e8400e29b41d4a716446655440000 - hyphens stripped for URLs and filenames.
- Braced: {550e8400-e29b-41d4-a716-446655440000} - Windows registry style.
- URN: urn:uuid:550e8400-e29b-41d4-a716-446655440000 - for semantic-web contexts.
All four represent the same 128-bit value - converting between them is just punctuation. When a system asks for a UUID, the hyphenated form is almost always what it wants.