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UUID Generator
A UUID generator produces version-4 universally unique identifiers, the 128-bit values used as primary keys, request IDs, file names, and tracking tokens when an identifier must be unique without a central authority handing out numbers. A v4 UUID draws its bits from randomness rather than a timestamp or sequence, so two systems can mint identifiers independently and stay collision-free in practice across the entire universe of records they will ever create.
This tool generates one to a hundred v4 UUIDs at a time using the browser’s cryptographic randomness, prefers the native crypto.randomUUID() where the browser exposes it, and lets the output be uppercased, stripped of hyphens, or wrapped in braces for the format a database or language expects. It is free, runs entirely in the browser, and never sends what it produces to a server.
🔒 Private: everything runs in your browser. Nothing you paste is uploaded.
How to use the UUID generator
Set how many identifiers are needed, pick the format your target system wants, and click Generate. The output is computed on the spot from cryptographic randomness, then copied or downloaded as a plain text file.
Generate version-4 UUIDs from real cryptographic randomness
Every identifier here is a version-4 UUID, meaning 122 of its 128 bits come from a random source while six are fixed to mark the version and variant defined by RFC 4122. The tool reads those bytes from the browser’s crypto interface, the same cryptographically secure generator used for keys and tokens, and never falls back to Math.random(), which is predictable and unsuitable for identifiers. With 122 random bits the odds of two generated UUIDs colliding are so small that, in practice, the values can be treated as unique without coordination between systems.
Match the output format to your database or language
The same UUID is written differently across stacks, so the format toggles reshape the output without changing its underlying value. Uppercase suits systems that store hex in caps, removing the hyphens yields the compact 32-character form some APIs and file names prefer, and wrapping in braces produces the registry-style format Microsoft tools and the .NET Guid type often expect. Toggling a format re-renders the existing batch instantly rather than drawing new randomness, so the identifiers stay stable while you settle on the exact shape your schema needs.
Generate in bulk, then copy or download
Seeding a test database, pre-allocating keys for a migration, or stubbing fixtures usually needs more than one identifier, so the count field produces up to a hundred UUIDs in a single click. Copy all sends the whole list to the clipboard, and Download saves it as a plain text file with one UUID per line, ready to paste into a seed script, a spreadsheet column, or an import file. Because nothing leaves the browser, the same batch can be regenerated safely even when the identifiers are headed for production systems.
UUID generator frequently asked questions
Q1What is a version-4 UUID?
A version-4 UUID is a 128-bit identifier whose value is drawn mostly from randomness, with six bits fixed to mark it as version 4 and to set the variant defined by RFC 4122. Unlike time-based versions it carries no timestamp or hardware address, so it leaks nothing about when or where it was created, which is why it is the common default for keys and tokens.
Q2Are these UUIDs cryptographically random?
Yes. The generator reads its bytes from the browser’s crypto interface, either crypto.randomUUID or crypto.getRandomValues, both of which are cryptographically secure random sources. It never uses Math.random, which is predictable and unsafe for identifiers. The output note shows which source produced your batch so you can confirm the randomness used.
Q3Can two generated UUIDs ever collide?
In practice, no. A version-4 UUID has 122 random bits, giving roughly 5.3 undecillion possible values, so the chance of generating the same one twice is negligible even across billions of identifiers. This is why distributed systems can mint UUIDs independently without a central authority and still treat them as unique without checking for duplicates.
Q4Does this tool send my UUIDs to a server?
No. Every identifier is generated in your browser with client-side JavaScript, and nothing is uploaded, logged, or stored. The Copy and Download actions run locally, and the tool keeps working offline once the page has loaded, which makes it safe to use for keys and tokens that will end up in production systems.
Q5What do the uppercase, no-hyphen, and braces options do?
They reshape how each UUID is written without altering its value. Uppercase converts the hex digits to capitals, no-hyphen produces the compact 32-character form some APIs and file names use, and braces wrap the value in curly brackets for the registry-style format common in Microsoft and .NET tooling. Toggling them re-renders the current batch instantly rather than generating new identifiers.
