UUID Generator

// HOW TO USE

1. 01Click Generate for a single v4 UUID, or Generate Bulk with the count selector for multiple at once.
2. 02Toggle Uppercase or Hyphens to match the format your system expects.
3. 03Click Copy next to any UUID, or Copy all to grab the whole list.

// WHEN TO USE

Use this when you need one or more valid v4 UUIDs for test fixture IDs, database record seeds, API request bodies, or mock response values. UUIDs are the most common identifier format in distributed systems — using randomly generated ones in tests avoids ID collision and prevents tests from depending on predictable sequential IDs. Generate in bulk when seeding a database or building a fixture file with multiple records.

// WHAT BUGS THIS FINDS

• Hardcoded test ID causes unique-constraint failure

  A test that always inserts the same hardcoded UUID fails on the second run if the ID already exists — generate fresh UUIDs per test run to prevent unique-constraint violations.

• UUID format mismatch (case or hyphens)

  An API that expects lowercase UUIDs receives uppercase from a test fixture, or a system that stores without hyphens receives a hyphenated value — the Uppercase and Hyphens toggles show both forms for verification.

• Sequential ID assumption exposed by UUID

  A feature that sorts or paginates by insertion order assumes auto-incrementing integer IDs — substituting UUID-based IDs in tests surfaces this assumption as a bug when sort order becomes unpredictable.

• UUID version mismatch rejected by validation

  A system validates that IDs are v4 (random) but a test fixture contains v1 (time-based) UUIDs — the version difference can cause validation rejections that only appear in production-like environments.

// QA USE CASES