UUID Generator

How to Use This Calculator

1. Select the UUID Version — v4 for general use, v7 for databases, v1 for time-based needs.
2. Set Quantity (1–20 UUIDs per generation).
3. Click calculate to generate. Each click produces a new set of random UUIDs.
4. Use the Professional tier to choose output format: standard, no-dashes, UPPERCASE, or Microsoft GUID {braces}.

Formula

Example

Frequently Asked Questions

• What is a UUID? ▼
  A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 8-4-4-4-12 hexadecimal characters (e.g., 550e8400-e29b-41d4-a716-446655440000). The probability of generating two identical UUID v4s is astronomically low — approximately 1 in 5.3 × 10^36.
• What is the difference between UUID v4, v1, and v7? ▼
  UUID v4 is entirely random (122 random bits) and the most widely used. UUID v1 incorporates the current timestamp and MAC address, making it traceable to a machine and time — a privacy concern. UUID v7 (RFC 9562, 2024) uses a Unix millisecond timestamp prefix followed by random bits, so UUIDs are sortable by creation time — ideal for database primary keys.
• What is a GUID and is it the same as UUID? ▼
  GUID (Globally Unique Identifier) is Microsoft's implementation of UUID. GUIDs are functionally equivalent to UUIDs. Microsoft often wraps them in braces: {550e8400-e29b-41d4-a716-446655440000}. Both follow RFC 4122 (now superseded by RFC 9562 for v6/v7/v8).
• Why use UUID v7 instead of v4 for databases? ▼
  UUID v4 is purely random, which causes severe index fragmentation in B-tree indexes (like PostgreSQL or MySQL primary key indexes). Every new v4 UUID inserts at a random position, requiring constant page splits. UUID v7's timestamp prefix ensures new UUIDs are always inserted at the end of the index, like auto-incrementing integers, giving much better write performance.
• What is the NIL UUID? ▼
  The NIL UUID is a special UUID with all 128 bits set to zero: 00000000-0000-0000-0000-000000000000. It is defined in RFC 4122 and used as a null or placeholder value, similar to null in programming. It is guaranteed to never be generated randomly.

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