UUID Generator: How to Generate Unique Identifiers for Databases, APIs, and Systems

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. Unlike auto-incrementing IDs, UUIDs are designed to be globally unique across all systems and time — no central coordination needed. This makes them essential for distributed systems, databases, APIs, and anywhere you need to avoid ID collisions.

Use the UUID Generator on TodayCalculator to create UUIDs in multiple versions instantly, with bulk generation support.

UUID Versions and When to Use Them

Version	Generation Method	Best For
UUID v4	Random (122 random bits)	Most applications. Simple, no dependencies.
UUID v1	Timestamp + MAC address	Time-ordered IDs. Traceable to source machine.
UUID v3	MD5 hash of namespace + name	Deterministic: same input always produces same UUID.
UUID v5	SHA-1 hash of namespace + name	Similar to v3 but more secure hashing.
UUID v7	Timestamp + random (RFC 9562)	Time-sortable, database-index-friendly.

Why Use UUIDs Instead of Auto-Increment IDs?

• No collisions across systems — Merge databases from different sources without ID conflicts
• Distributed-friendly — Generate IDs offline on any device without a central server
• Security — UUIDs are unpredictable, unlike sequential IDs (no ID enumeration attacks)
• Database sharding — UUIDs work naturally with horizontal scaling
• Frontend ID generation — Create IDs on the client side before the server round-trip

How to Use the UUID Generator

1. Select the UUID version you need (v4 is the most common)
2. Choose the output format: standard (with hyphens), no hyphens, or uppercase
3. Set the quantity: generate 1 to 100 UUIDs at once
4. Click Generate and copy the results in one click

UUID format follows the 8-4-4-4-12 pattern: 550e8400-e29b-41d4-a716-446655440000. The version number appears in the 13th character (e.g., “4” for v4) and the variant in the 17th character.

Generate your UUIDs instantly at the UUID Generator — free, no registration needed, works offline in your browser.