Free UUID generator

Generate UUID v4, v7, v1, or a Microsoft-style GUID, one at a time or a thousand at once. Every ID is created on your device with the Web Crypto API. Nothing is sent to a server, and closing the tab clears it.

How manyup to 1,000 per batch

Uppercase Braces {…} Hyphens

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How the UUID generator works

Choose a version and format

Pick v4, v7, v1, or Nil, set how many you need, and choose uppercase, braces, or no hyphens for a GUID-style value.

Generate on your device

The random bits come from the Web Crypto API, the same secure source your browser uses for TLS. Nothing you generate is sent anywhere.

Copy or download

Copy a single ID or the whole batch, or download a large list as a plain text file.

Private by design: nothing leaves your browser

A UUID is often the primary key for a record in a system you are building, so the identifier for that record should not take a detour through someone else's server on the way in. This generator creates every value locally:

100% client-side

The random bytes come from crypto.getRandomValues, your browser's own cryptographically secure generator. No network request is made to produce an ID.

Nothing stored or logged

There is no account and no analytics on what you generate, so nothing is kept between visits. Reload the page and the batch is gone from memory.

No hardware leak

The v1 option uses a random node instead of your machine's network card address, so a timestamp UUID never carries a hardware identifier out of the page.

Which version to use

v4 is the default: 122 random bits, unordered, right for most database keys and request IDs.
v7 packs a millisecond timestamp into the front, so the IDs sort by creation time and keep database indexes tight on high-insert tables.
v1 is timestamp-based and exists mainly for compatibility with older systems that expect it.
Nil is the all-zero UUID, useful as a placeholder or a "no value" sentinel.

Built for developers and technical teams

Anyone who needs a unique identifier they can trust, generated somewhere they control. BlockSurvey takes the same position on research data with zero-knowledge surveys, where responses are encrypted before they ever reach a server.

Developers

Seed a database, mock an API response, or grab a request ID for a log line without pulling in a library or hitting an endpoint.

QA & data teams

Generate a batch of test keys, download them as a text file, and load them straight into a fixture or a spreadsheet.

Windows & .NET developers

Turn on uppercase and braces to get the exact GUID format that Microsoft tooling and registry keys expect.

Building something that handles sensitive data?

BlockSurvey runs on zero-knowledge surveys, so the responses you collect are never sold or mined. Responses are encrypted on the respondent's device, so the server stores nothing readable.

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Frequently asked questions

Is this UUID generator free?

Yes, completely free with no sign-up and no cap beyond the 1,000-per-batch limit, which is there only to keep the page responsive.

Are the UUIDs generated on a server?

No. Every UUID is generated in your browser with the Web Crypto API, which is the same cryptographically secure random source the browser uses for TLS. The page makes no server request to produce an ID, so there is nothing to log or keep, and identifiers for private systems never leave your machine.

Which UUID version should I use?

Use v4 unless you have a reason not to. v4 is 122 random bits and is the safe default for database keys, request IDs, and anything that needs to be unique but not ordered. Choose v7 when you want the IDs to sort by creation time, which keeps database indexes tighter than v4. v1 exists mainly for compatibility with older systems that expect a timestamp-based ID.

How likely is a UUID v4 collision?

Negligible for any real workload. A v4 UUID has 122 random bits, so you would need to generate roughly 2.7 quintillion of them before the chance of a single collision reaches one in a billion. In practice you can treat each v4 as unique without checking.

What is the difference between a UUID and a GUID?

They are the same 128-bit value. GUID is Microsoft's name for a UUID, and Microsoft tooling usually shows it uppercase and wrapped in braces, for example {A1B2C3D4-...}. Turn on the uppercase and braces options here to produce that format; the underlying bits are identical.

Is UUID v7 safe to use in production?

Yes. v7 was standardised in RFC 9562 in 2024 and is widely supported. It packs a 48-bit Unix millisecond timestamp into the front of the ID, then fills the rest with random bits, so the values are both time-sortable and practically unique. It is a good default for primary keys in high-insert tables.

Do timestamp-based UUIDs leak information?

v1 and v7 both embed the creation time, so anyone holding the UUID can read roughly when it was made. v1 historically also embedded the machine's network card address; this tool uses a random node instead, so no hardware identifier is exposed. If you do not want the creation time to be readable, use v4.

Can I use this offline?

Yes. Once the page has loaded you can disconnect from the internet and keep generating, because everything runs in your browser.

Do you store the UUIDs I generate?

No. Every ID is generated in your browser with the Web Crypto API and never sent to a server, so there is nothing to log or store on our side.

How is this different from a paid UUID generator?

The algorithms (v4, v7, v1) are open standards, so the output is the same everywhere. This one runs entirely client-side with no sign-up and no cap beyond the 1,000-per-batch limit, where paid tools mostly just add an account and a rate limit on top of the same generation logic.