UUID v4 Generator

Generate random UUID v4 values

A UUID version 4 is a 128-bit identifier generated from random or pseudorandom data, with fixed bits marking its version and variant. Generate one value or a batch of up to 1,000, and optionally output uppercase characters or remove the presentation hyphens.

The standard lowercase representation has 32 hexadecimal digits in five groups: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is 8, 9, a, or b. Removing hyphens changes the text representation, not the underlying 128-bit value.

How to use the UUID v4 generator

1. Set Count to the number of identifiers required.
2. Keep Hyphens enabled for the conventional UUID text format, unless the receiving system requires 32 compact hexadecimal digits.
3. Select Upper Case only when required by an existing format or convention.
4. Click Generate, then copy or download the values.

UUIDs are commonly used as database identifiers, request or correlation IDs, object keys, test data, and identifiers created without coordinating a central sequence.

UUID v4 randomness and uniqueness

RFC 9562 defines UUIDv4 using random or pseudorandom data and reserves the version and variant bits, leaving 122 random bits. The very large space makes accidental collisions unlikely when generation uses a suitable random source, but uniqueness is probabilistic rather than mathematically guaranteed.

A UUID is an identifier, not a secret. Do not assume UUIDv4 values are unguessable authorization tokens, and do not place sensitive information in them. Applications should still enforce database uniqueness constraints when duplicates would be harmful.

UUID v4 FAQ

Is UUID v4 the same as GUID?

GUID is a term commonly used for identifiers with the same familiar hexadecimal form, especially in Microsoft systems. Check the consuming system’s byte-order and formatting requirements when exchanging a binary GUID rather than its canonical text representation.

Can I sort UUID v4 values by creation time?

UUIDv4 does not encode a timestamp, so lexical order does not represent creation order. Consider the UUID v7 Generator when a time-ordered UUID is appropriate.

When should I use UUID v3 or v5 instead?

Use a name-based UUID when the same namespace and name must deterministically produce the same identifier. UUID v3 uses MD5, while UUID v5 uses SHA-1 for that standardized mapping.