What UUID version does this generator create?

Version 4, the randomly generated variant, which is the most commonly used UUID version for general-purpose unique identifiers.

Can two generated UUIDs ever be the same?

Mathematically possible but practically negligible — a version 4 UUID has about 5.3 x 10^36 possible values, so collisions are not a realistic concern for virtually any application.

Can I generate multiple UUIDs at once?

Yes, use the bulk option to generate a list of UUIDs in one pass instead of generating them one at a time.

UUID Generator

Generate, validate, and explore UUID v4 identifiers. Bulk generate up to 100 UUIDs at once.

Generated UUID v4

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Format Breakdown

Bulk Generate

Count:

UUID Validator

How to use

Click Generate New to create a cryptographically random UUID v4.
Use Copy UUID to copy it to your clipboard.
Toggle Case switches between lowercase and uppercase formats.
NIL UUID inserts the special all-zeros UUID (00000000-0000-0000-0000-000000000000).
The format breakdown shows what each section of the UUID represents with color coding.
Enter any UUID in the validator to check if it is valid and which version it is.
Set a count (1–100) and click Generate List for bulk UUID generation.

About UUID Format

A UUID (Universally Unique Identifier) is a 128-bit value represented as 32 hexadecimal digits in 5 groups separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

time_low

First 8 chars — 32 bits

time_mid

4 chars — 16 bits

time_hi + version

4 chars — M = version digit

clock_seq

4 chars — N = variant bits

node

12 chars — 48 bits

In UUID v4, the M digit is always 4 and the N digit is 8, 9, a, or b. All other digits are random, giving approximately 2¹²² possible values.

About this UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit value used to identify records, sessions, devices, and objects without needing a central authority to hand out sequential IDs. Two independently generated UUIDs are, for all practical purposes, guaranteed never to collide.

What a UUID looks like

A UUID is written as 32 hexadecimal digits split into five groups by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. In a version 4 (random) UUID, the "4" in the third group marks the version, and the first character of the fourth group is always 8, 9, a, or b, which marks the variant.

Why collisions are practically impossible

A version 4 UUID has 122 random bits (the other 6 bits are fixed as version/variant markers), giving roughly 5.3 × 10³⁶ possible values. You would need to generate about a billion UUIDs every second for 85 years before the probability of a single collision reached 50%.

Common uses

Database primary keys, especially in distributed systems where multiple servers insert records without coordinating
Session tokens and API request IDs for tracing a single request through logs
File names and object storage keys where uniqueness must be guaranteed without checking existing names
Test data and placeholder identifiers during development