UUID Generator
Cryptographically random v4 UUIDs, one or a thousand at a time. 100% free, no signup. Everything runs in your browser.
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This UUID generator produces version 4 UUIDs using your browser's own crypto.randomUUID and getRandomValues functions, which draw from a cryptographically strong random source. Generate one, or up to 1,000 in a batch, flip them to uppercase or strip the hyphens if your system wants them compact, and copy one or the whole list in a click.
Because generation happens in your browser, the IDs are never transmitted anywhere, not even to me. They exist on your screen and in your clipboard, and nowhere else.
How to use
- Open the page and a fresh UUID is already waiting for you.
- Click generate for a new one whenever you need it.
- For bulk, enter how many you want, up to 1,000, and generate the batch.
- Toggle uppercase or remove hyphens to match the format your system expects.
- Copy a single UUID with its own button, or copy the entire list at once.
- Generate again as often as you like. There is no limit and no counter.
Why use our uuid generator?
The random source is the part worth caring about. These UUIDs come from the browser's crypto API, the same generator trusted for cryptographic keys, not from Math.random, which is fast but predictable enough to have caused real security incidents when misused for identifiers. A version 4 UUID is only as good as its randomness, so I use the strong source and say so plainly.
Now the honest collision math, because most sites either dodge it or oversell it. A v4 UUID carries 122 random bits. To reach even a 50 percent chance of a single collision you would need to generate around 2.7 quintillion UUIDs, which at a billion per second would take about 86 years. The chance is not zero, and anyone telling you it is zero is rounding, but it is small enough that every serious system treats v4 IDs as unique without checking. The format itself is standardized in RFC 4122 if you want the details from the source.
The uppercase and no-hyphen options exist because databases and vendors refuse to agree. SQL Server likes to display GUIDs in uppercase, plenty of APIs want the compact 32-character form, and reformatting by hand invites exactly the copy-paste errors that unique identifiers exist to prevent. It is the same 128 bits either way, just dressed differently.
What I refuse to add: a server-side history of generated IDs, or an API that puts me in the middle of your identifiers. A UUID generator you have to trust is a contradiction, so this one is verifiably local. Load the page, switch off your Wi-Fi, and it keeps working, which is the whole proof.
If you are generating IDs, you are probably neck-deep in adjacent chores too. The password generator covers values that must stay secret, which UUIDs are not, and the JSON formatter tidies the payloads those IDs inevitably end up inside.
Who is this tool for?
Developers seeding test data are the heaviest users. A database fixture with 500 rows wants 500 unique keys, and the bulk mode hands you all of them in one copy, formatted the way your schema expects. It beats writing a throwaway script every time, which is what I did for years before finally building this.
One-off IDs come up more than people expect: a correlation ID for reproducing a bug, a unique key for a config entry, a stable identifier for a webhook or feature flag. Open the page, copy the ID that is already waiting, close the page. Ten seconds, done.
Debugging API traffic is a quieter use. UUIDs turn up as request IDs, session identifiers and resource keys throughout modern payloads, and having a generator beside the JWT decoder covers both halves of poking at an authenticated API by hand.
Non-developers use UUIDs more than they realize: unique codes for spreadsheet rows, asset tags for inventory, identifiers for files shared across teams. Anywhere the requirement is these must never accidentally collide, a v4 UUID is the lazy answer that happens to be correct.
Frequently asked questions
A 128-bit identifier where 122 bits are random and six are fixed to mark the version and variant. Written in hex it looks like 8-4-4-4-12 characters, with a 4 leading the third group. Unlike version 1, it encodes nothing about your machine or the current time, it is pure randomness.
In principle yes, in practice no. You would need quintillions of generated IDs before a collision becomes even a coin flip, and decades of generation at absurd rates to get there. Systems worldwide bet on v4 uniqueness daily, and the math is why they keep winning.
Please do not. A v4 UUID from a crypto source is unpredictable, but UUIDs get logged, indexed and passed around in URLs precisely because nobody treats them as secrets. For anything that must stay confidential, generate a purpose-built secret with my password generator instead.
Nothing but vocabulary. GUID is Microsoft's name for the same 128-bit structure, and the terms are interchangeable in practice. If a vendor tool demands GUIDs in uppercase, the uppercase toggle here produces exactly what it wants.
Some databases, APIs and file-naming schemes want the compact 32-character form, either to save space or because their validation was written that way. The hyphens are purely cosmetic separators, so stripping them loses nothing. Add them back and it is the same identifier.
Yes. crypto.getRandomValues is a cryptographically strong generator seeded by the operating system, the same machinery browsers rely on for TLS. It is a different animal from Math.random, and it is the only source this tool uses.
No, and I could not even if I wanted to, because generation never leaves your browser. No server sees them, no analytics records them. If you need the same ID tomorrow, save it yourself, because I genuinely have no copy.