Overview
Somewhere in nearly every database, API and distributed system, things need names that will never collide — not today, not on another server, not in ten years. The UUID is the industry's answer: a 128-bit identifier, standardised and random enough that two independently generated ones will not match in the lifetime of the universe. Version 4 is the random flavour, and this page mints them properly.
You control the batch and the format. Generate anywhere from one to fifty at a time, keep the classic hyphenated grouping or strip it to a compact 32-character string, switch to uppercase for systems that expect it, then copy the batch or download it as a file. The randomness comes from your browser's cryptographic source, so the IDs are as unpredictable as UUIDs are supposed to be.
What makes a UUID version 4 special?
The 128 bits are not entirely random: six bits are fixed to mark the version (4) and variant, leaving 122 bits of randomness. That structure is what makes a v4 UUID recognisable — the third group's first digit is always 4, and the fourth group's first digit is 8, 9, a or b. Software can verify the format at a glance, which is why the generator sets those bits correctly rather than randomising everything.
With 122 random bits, the collision odds are famously negligible: generating a billion UUIDs per second for a century still leaves the chance of a single duplicate far below one in a billion. That is the whole point — IDs you can create anywhere, with no central registry and no coordination, and simply trust to be unique.
Features
- Batches of 1 to 50 per click — one for testing, dozens for seeding.
- Proper v4 format with version and variant bits set correctly.
- Hyphenated or compact: classic 8-4-4-4-12 grouping or a 32-character string.
- Uppercase option for systems and conventions that expect capitals.
- Copy-all and download for moving IDs into code or fixtures.
- Cryptographic randomness behind every identifier.
- Instant and private — no server, no account, no log.
Benefits
- Unique IDs without infrastructure. No registry, no coordination, no collisions.
- Test data in seconds. Fifty well-formed IDs for fixtures and mocks.
- Format on demand. Match whatever the consuming system expects.
- Trustworthy randomness. Secure source, correct version bits.
Who can use it
Developers seeding databases and writing tests, API designers minting resource identifiers, QA engineers needing unique test values, and data engineers generating surrogate keys. Anyone who has ever used an auto-increment ID where a distributed system needed independence will appreciate the alternative.
How to use
- Set how many UUIDs you need, from 1 to 50.
- Choose hyphenated or compact format, and lower or upper case.
- Press generate and review the batch.
- Copy all to the clipboard or download as a text file.
- Paste into your code, fixtures or database seeds.
Frequently asked questions
Will two UUIDs ever collide?
For practical purposes, no. With 122 random bits, you would need to generate around 2^61 UUIDs — billions per second for a century — before the collision chance reached fifty percent. Your batches of fifty are, to put it mildly, safe. The guarantee is statistical rather than absolute, but the statistics are overwhelming.
What is the difference between v1 and v4?
Version 1 embeds a timestamp and a machine identifier, which makes IDs sortable by time but leaks information about when and where they were created. Version 4 is purely random, revealing nothing. Unless you specifically need time-ordering, v4 is the safer default — and it is what this generator produces.
Should I store UUIDs with or without hyphens?
Either works as long as you are consistent. Hyphenated is the canonical text form and easier for humans to read; compact saves four characters per ID and suits systems that treat IDs as opaque tokens. Databases often store the raw 16 bytes and format on display — the generator covers the text side of that.
Are these UUIDs suitable as API keys?
They are unpredictable enough, since they come from a cryptographic random source — but API keys usually want additional properties like prefixes for identification and revocation handling. For internal identifiers, correlation IDs and test fixtures, v4 UUIDs are exactly right.
Why does the third group always start with 4?
Those are the version bits — the standard reserves them to declare “this is a version-4 UUID.” Similarly the fourth group starts with 8, 9, a or b to mark the variant. A validator can confirm the format from those nibbles alone, which is why the generator sets them deliberately instead of randomising.
Conclusion
One click, fifty collision-proof identifiers, correctly formatted. Generate the batch, copy it into your project, and never coordinate an ID again.