Generate random UUIDs (Universally Unique Identifiers).
The UUID Generator creates random UUIDs (Universally Unique Identifiers, also called GUIDs) using UUID version 4, the format based on cryptographically random bits rather than a device address or timestamp. Each UUID is a 36-character string — 32 hexadecimal digits arranged in the standard 8-4-4-4-12 pattern — with a low enough collision probability that two independently generated UUIDs can be treated as unique for all practical purposes, even across separate systems with no coordination between them. This makes UUIDs a common choice for database primary keys, API resource identifiers, and unique IDs in distributed systems where multiple services need to generate IDs independently. Choose how many you need, click Generate, and copy individual values or the whole batch at once. Generation happens locally in your browser using the same cryptographic random number source browsers use for other security-sensitive operations, so nothing about the values you generate is transmitted or logged anywhere.
Made for developers. Typical uses:
A generated UUID v4 looks like "3fa85f64-5717-4562-b3fc-2c963f66afa6" — 32 hexadecimal digits arranged in the standard 8-4-4-4-12 pattern. The leading "4" in the third group marks it as version 4 (randomly generated). The tool produces a fresh, independent value like this each time you click Generate — there's nothing special about this particular example string, it's just illustrating the format.
A UUID guarantees practical uniqueness, not secrecy — they're often logged, displayed in URLs, or stored in plain database columns, so they shouldn't be relied on as an unguessable secret or authentication token the way a dedicated random token would be.
Accuracy: Output is tested against known inputs. For production code, review the result and run your own tests.
Expert Tip
Use UUIDs for record identifiers, not for sort order — because v4 UUIDs are random, sorting a table by UUID gives no meaningful chronological order. Add a separate timestamp or sequence column if you need to know creation order.
A UUID (universally unique identifier), also called a GUID, is a 128-bit value written as 36 characters: 32 hexadecimal digits in the pattern 8-4-4-4-12. The UUID Generator makes version 4 UUIDs, which are built from random bits. The digit that starts the third group is always 4, and the digit that starts the fourth group is always 8, 9, a or b, which is how a program can recognise the version and variant.
Choose how many you need (1, 5, 10, 20, 50 or 100) and the format: standard lowercase with dashes, uppercase with dashes, or no dashes at all. They are created with your browser's secure random number generator, and nothing is sent to a server. Each result can be copied on its own, or all can be copied together.
A version 4 UUID has 122 random bits, which gives about 5.3 × 10^36 possible values. Collisions are possible in theory but not in practice: you would need to generate roughly 2.7 × 10^18 UUIDs before the chance of any two matching reached 50 percent. That is why systems can create identifiers independently, on many machines, without checking with a central database.
UUIDs suit database keys for records created on several servers or offline, file names that must not clash, correlation IDs in logs and test data.
To check that a string is a valid UUID, use the UUID Validator. For random numbers in a range use the Random Number Generator, and for secret values such as passwords use the Password Generator. To fingerprint data, use the Hash Generator.
Version 4 is the random type and the most widely used. Version 1 combines a timestamp with a machine identifier, which can reveal when and where it was made. Newer time-ordered versions, such as version 7, put a timestamp first so that new identifiers sort in the order they were created, which keeps database indexes tidy. This tool creates version 4 only, which is the right choice when you want identifiers that reveal nothing about their origin.
Store UUIDs in a native UUID or binary column when your database has one, because the 36-character text form uses more than twice the space of the 16 bytes inside it. Compare them case-insensitively, since lowercase and uppercase forms are the same value. Remove the dashes only if the system you are feeding insists on it, and keep one format throughout a project to avoid mismatches.
Base64 is not encryption and a hash cannot be reversed. See what each does, where JWTs and URL encoding fit, and how to pick MD5, SHA-256 or a password hash.
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