UUID Generator
Generate random UUID values for apps, databases, and tests.
UUID
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UUID Generator
Create a UUID instantly and copy it for development or testing.
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How To Use The UUID Generator
Press Generate and a fresh version-4 UUID appears instantly in the output box, ready to read or reuse. Press Copy to put it on your clipboard so you can paste it straight into your code, a database row, a config file, or a test fixture. Each click produces a brand-new random value, so you can generate as many identifiers as you need in a row without any of them repeating. Nothing is pre-filled and there are no settings to configure: the tool does one job and does it the moment you ask.
What A UUID Is And How It Works
A UUID (Universally Unique Identifier), also called a GUID on Microsoft platforms, is a 128-bit number designed so that anyone, anywhere, can mint one without checking a central registry and still be confident it will not clash with anyone else's. That property is what makes UUIDs so useful in distributed systems: two servers that have never communicated can each create an identifier and safely assume the results are different. A version-4 UUID achieves this through sheer randomness rather than coordination. Of its 128 bits, 6 are reserved to record the version and variant, leaving 122 truly random bits, which is the source of its astronomical address space.
UUID Versions And The 8-4-4-4-12 Format
A UUID is always written as 32 hexadecimal digits split into five hyphen-separated groups. The version digit and the variant digit sit at fixed positions, so you can identify how a UUID was created just by reading it. The table below summarises the formats and versions you are most likely to meet.
| Aspect | Detail | Example |
|---|---|---|
| Format | 32 hex digits, grouped 8-4-4-4-12 | 550e8400-e29b-41d4-a716-446655440000 |
| Version 1 | Time-based: timestamp plus MAC address | ...-11d4-... (digit 1) |
| Version 4 | Random: 122 random bits (this tool) | ...-41d4-... (digit 4) |
| Version digit | First character of the third group | 4 for v4 |
| Variant digit | First character of the fourth group | 8, 9, a or b |
| Total values (v4) | 2^122 possibilities | ~5.3 undecillion |
The hyphens and grouping are purely cosmetic, but they are part of the canonical text form and most parsers expect them.
Worked Example: Reading A UUID
Take 550e8400-e29b-41d4-a716-446655440000. Counting the groups gives 8, 4, 4, 4 and 12 hexadecimal digits. The third group is 41d4, and its leading 4 tells you this is a version-4 (random) UUID. The fourth group is a716, and its leading a is the variant marker that says the value follows the standard RFC layout. Everything else is random, which is exactly why you cannot infer when or where the identifier was created.
Why This Tool Is Useful
Whenever you need an identifier that will not collide with another, typing one by hand is error-prone and predictable. This generator gives you a correctly formatted, genuinely random UUID in a single click for database primary keys, message and request IDs, idempotency keys for APIs, file or upload names, test fixtures, and seed data. Because each value is independent, you can grab one for a quick experiment or dozens for a batch of test rows without worrying about duplicates or reaching for a code snippet.
Accuracy And Privacy
The UUIDs are produced entirely in your browser using its built-in cryptographic random number generator, the same source recommended for version-4 identifiers. Nothing you generate is uploaded, logged, or stored on any server, so the values are yours alone and disappear when you leave the page. One caution worth repeating: a UUID is an identifier, not a secret. It is fine as a public-facing key, but it should never be used as a password, an API token, or anything that grants access on its own.
FAQ
How unlikely is a UUID collision?
Extremely unlikely. A version-4 UUID has 122 random bits, which is about 5.3 undecillion possible values. To reach even a one-in-a-billion chance of a single collision you would need to generate roughly 103 trillion UUIDs. For any realistic application the odds are so small that they are treated as effectively zero.
What is the difference between UUID v4 and v1?
Version 1 is time-based: it combines the current timestamp with the machine's network (MAC) address, so the values are roughly ordered by creation time but can leak information about where and when they were made. Version 4 is almost entirely random, which reveals nothing about the host and is the safer default for most applications. This tool generates version-4 UUIDs.
Are UUIDs guaranteed to be unique?
Not mathematically guaranteed, but practically yes. A v4 UUID relies on randomness rather than a central authority, so two identical values are theoretically possible. The probability is so vanishingly small that systems worldwide rely on UUIDs as unique identifiers without any coordination between them.
What is the UUID format?
A UUID is 32 hexadecimal digits displayed in five groups separated by hyphens in an 8-4-4-4-12 pattern, for example 550e8400-e29b-41d4-a716-446655440000. The third group starts with the version digit (4 for v4) and the fourth group starts with a variant digit (8, 9, a, or b).
Can I use a UUID as a database primary key?
Yes, and it is a common pattern. UUIDs let you generate a key in the application before inserting a row and avoid exposing sequential auto-increment IDs. The trade-off is that random v4 keys are larger than integers and can fragment index ordering, so high-write systems sometimes prefer a time-ordered variant or store the UUID as a binary column for performance.