UUID v4 & v7 Generator

What Are UUIDs?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 9562 (formerly RFC 4122). UUIDs are designed to be globally unique without requiring a central authority. UUID v4 uses 122 bits of cryptographically random data, making collisions astronomically unlikely — the probability of a duplicate is roughly 1 in 2¹²² (about 5.3 × 10³⁶). UUID v7 embeds a Unix timestamp in the first 48 bits followed by random data, producing identifiers that are both unique and chronologically sortable — ideal for database primary keys. The Nil UUID (all zeros) is a special sentinel value used to represent an empty or missing identifier.

How to Use This UUID Generator

1. Select the UUID version: v4 (random), v7 (timestamp-based), or Nil.
2. Adjust the count slider to generate between 1 and 100 UUIDs at once.
3. Toggle Uppercase if you need capital hex characters.
4. Click Generate or change settings — UUIDs are created instantly.
5. Copy individual UUIDs or all at once using the copy buttons.

Common Use Cases for UUIDs

• Database primary keys — Use UUID v7 as primary keys in distributed databases — they are unique, sortable by creation time, and do not require a central sequence generator.
• API request tracing — Assign a UUID to each API request for end-to-end tracing across microservices and logging systems.
• Session and token identifiers — Generate UUID v4 values for session IDs, CSRF tokens, or temporary access tokens where unpredictability is important.
• File and resource naming — Use UUIDs as unique filenames for user uploads to avoid collisions and prevent information leakage from sequential names.
• Test data generation — Quickly generate batches of unique identifiers for populating test databases, mock APIs, or fixture files.