A UUID (Universally Unique Identifier) is a 128-bit number represented as 32 hexadecimal digits grouped as 550e8400-e29b-41d4-a716-446655440000. UUID v4 is fully random and the most widely used version for database IDs, session tokens, and API keys.

What is the difference between UUID and ULID?

UUID v4 is completely random and not chronologically sortable. ULID encodes a millisecond timestamp in the first 10 characters, making it sort chronologically — better for database primary keys where sequential ordering improves index performance.

Is the UUID generator free?

Yes — generate UUID v4, ULID, and NanoID identifiers free with no signup required.

Dev Tool

UUID Generator

Generate UUIDs (v1, v4, v5), ULIDs and Nano IDs. Bulk generation, custom formats and UUID validator included.

⚙️ Select UUID Type

Click Generate or press Space

Bulk:

✅ UUID Validator

🎲

UUID v4

Most common — 122 bits of cryptographic randomness. Collision probability is negligible.

⏱️

UUID v1

Time-based with MAC address component. Sortable by creation time.

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ULID

Universally Unique Lexicographically Sortable Identifier — sortable and URL-safe.

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Nano ID

URL-safe, compact, faster than UUID v4. Great for public-facing IDs.

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information. The standard format is 8-4-4-4-12 hexadecimal digits separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

What is the difference between UUID v1 and v4?

UUID v1 is time-based and includes the creation timestamp and MAC address, making it sequential and traceable. UUID v4 is fully random, offers better privacy and is far more commonly used in modern applications.

What is a ULID?

ULID (Universally Unique Lexicographically Sortable Identifier) combines a 48-bit timestamp with 80 bits of randomness. Unlike UUID v4, ULIDs sort naturally by creation time making them ideal for database primary keys.

UUID Generator

Frequently Asked Questions

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