UUID Generator — Generate UUID v4, v1, Bulk UUIDs & More Free
Generate cryptographically secure UUIDs (v4 random), timestamp-based UUIDs (v1), ULID, Nano IDs, and bulk UUIDs in any format — instantly in your browser. Perfect for databases, APIs, testing, and development workflows.
⚡ Generated using crypto.getRandomValues() — cryptographically secure. Zero data stored.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to identify objects in computer systems. The standard format is 32 hexadecimal digits displayed in 5 groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be globally unique without requiring a central registration authority.
This generator uses the Web Crypto API (crypto.getRandomValues()) — the same cryptographically secure randomness used in security applications — to generate truly unpredictable UUIDs entirely in your browser.
UUID v1 vs v4 vs ULID — Which Should You Use?
| Type | Basis | Sortable | Best For |
|---|---|---|---|
| UUID v4 | Random | No | General purpose, databases, APIs — most widely used |
| UUID v1 | Timestamp + MAC | Yes (time) | Ordered logs, event tracking — leaks MAC address |
| ULID | Timestamp + Random | Yes | Databases needing sort order + uniqueness |
| Nano ID | Random | No | Short URLs, tokens — smaller than UUID |
| Short UUID | Random alphanumeric | No | Human-readable IDs, slugs |
Frequently Asked Questions
What is a UUID?
UUID is a 128-bit unique identifier following the RFC 4122 standard. The standard format is 32 hex characters in groups of 8-4-4-4-12, like: 550e8400-e29b-41d4-a716-446655440000. They are used as primary keys in databases, tokens in APIs, and unique identifiers throughout software systems.
Are UUID v4s truly unique?
UUID v4 uses 122 bits of randomness (2^122 ≈ 5.3 × 10^36 possible values). The probability of generating two identical v4 UUIDs is so small that it's practically impossible — you'd need to generate over 1 billion per second for 85 years to have a 50% chance of a single collision.
What is the difference between UUID v1 and v4?
UUID v1 is generated using the current timestamp and the machine's MAC address — it's time-sortable but can leak identifying information. UUID v4 is entirely random and is the recommended choice for most applications where you don't need time-ordering.
What is a ULID?
ULID (Universally Unique Lexicographically Sortable Identifier) combines a 48-bit timestamp with 80 bits of randomness. Unlike UUIDs, ULIDs are lexicographically sortable, making them ideal for database primary keys where sort order matters.
Is this UUID generator safe to use for production?
Yes. This tool uses the browser's crypto.getRandomValues() API — a cryptographically secure pseudo-random number generator (CSPRNG) — the same one used in security-critical applications. The generated UUIDs are suitable for production use.