UUID Generator

Generate universally unique identifiers (UUIDs) online. Supports v4 (random), v1 (time-based), and bulk generation. Validate any UUID instantly.

UUID v4 — Randomly Generated

Generated using crypto.randomUUID() — cryptographically secure randomness.

UUID Validator

Paste any UUID to validate its format and detect its version.

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. Standardised as RFC 4122, UUIDs are represented as 32 hexadecimal digits grouped by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx.

The M digit indicates the version (1–5) and N indicates the variant. v4 UUIDs use random data and are the most widely used type.

Frequently Asked Questions

What is the difference between UUID v1 and v4?

UUID v1 is generated from the current timestamp and the MAC address of the machine, making it time-ordered but potentially traceable. UUID v4 is entirely random (122 random bits), making it unpredictable and privacy-safe. v4 is recommended for most use cases.

Are UUID v4 values truly unique?

Yes, for all practical purposes. With 2^122 possible values (~5.3 × 10^36), the probability of generating two identical v4 UUIDs is astronomically small. You would need to generate about 2.7 × 10^18 UUIDs before having a 50% chance of a collision.

Can I use UUIDs as database primary keys?

Yes. UUIDs are commonly used as primary keys, especially in distributed systems where auto-increment integers would cause conflicts. The trade-off is slightly larger storage (16 bytes vs 4–8 bytes for integers) and reduced index locality for v4 UUIDs. UUID v7 (time-ordered random) is gaining popularity for databases.

What does nil UUID (all zeros) mean?

The nil UUID (00000000-0000-0000-0000-000000000000) is a special UUID with all 128 bits set to zero. It is typically used as a sentinel or placeholder value to represent the absence of a real UUID, similar to null in programming.