Guides5 min read
What Is a UUID? (And How to Generate One)
A UUID is a 128-bit identifier random enough to treat as unique without checking a database. Here's how UUID v4 works and how to generate one.
UUID generator
Generate random UUID v4 identifiers, instantly. Free, private — nothing leaves your browser.
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Everything you need for UUIDs
Bulk generation
Generate 1 to 100 UUIDs at once, not one at a time.
Instant, no install
Runs on crypto.randomUUID() — no library, no server round-trip.
100% private
Every UUID is generated in your browser. Nothing is uploaded or logged.
Copy or download
Copy a single ID, copy the whole batch, or download a .txt file.
Generate a UUID in three steps
- 1
Pick your format
Toggle hyphens, uppercase, and braces to match what your code or database expects.
- 2
Set how many you need
Generate 1 or up to 100 UUIDs at once — useful for seeding test data or filling out a batch of records.
- 3
Copy or download
Copy a single UUID, copy the whole batch, or download it as a .txt file.
Built for developers, testers, and database work
A UUID (or GUID) is a 128-bit identifier that's practically guaranteed unique without coordinating with a central authority — useful anywhere you need an ID that won't collide.
Seeding test data
Fill out mock database rows or fixtures with real, collision-free unique IDs.
Primary keys and record IDs
Generate an ID for a new record without a round-trip to your database's own UUID function.
API testing and mocking
Quickly grab request IDs, session tokens, or correlation IDs for a test payload.
Config and env values
Generate a one-off identifier for a config file, feature flag key, or tracking value.
Frequently asked questions
What UUID version does this generate?
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Version 4 (RFC 4122) — a randomly generated 128-bit identifier, the most commonly used UUID version for general-purpose unique IDs. It's generated with the browser's own crypto.randomUUID() API, the same cryptographically secure random source used for security-sensitive values.
How unlikely is a UUID collision?
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Effectively zero for any real-world use. A v4 UUID has 122 random bits, so you'd need to generate roughly a billion UUIDs per second for about 85 years before a 50% chance of one collision.
Is my data uploaded anywhere?
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No. Every UUID is generated entirely in your browser — nothing is sent to a server.
Can I generate UUIDs without hyphens or in uppercase?
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Yes — toggle the Hyphens and Uppercase options above the results. Both apply live to every UUID already generated, so you don't need to regenerate to see the new format.
What are the curly braces used for?
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Some Windows APIs and COM interfaces expect a GUID wrapped in braces, like {3b12f1df-5232-4e0e-8a68-d20c8dfbe5c8}. Toggle Braces on if that's the format your target expects.
What's the difference between a UUID and a GUID?
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None in practice — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier format standardized as UUID in RFC 4122. The values are interchangeable.
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