UUID v4 Generator

About this generator

Every seeded database, test fixture, and mock payload needs identifiers that look like the real ones your application assigns. Using auto-increment integers in test data works locally but often breaks integration tests that expect UUIDs. This tool generates correctly formatted RFC 4122 version 4 UUIDs you can drop directly into seed scripts, JSON fixtures, or API payloads. The count input lets you produce 1 to 20 UUIDs at once. Each is generated with the version nibble fixed to 4 and the variant bits set correctly for RFC 4122, so they pass any UUID validator. The format is the standard 8-4-4-4-12 hyphenated hex string. Copy a batch into your seed data or use individual IDs as primary keys in fixture records. For production identifiers, generate UUIDs in your own application runtime using a cryptographically secure source — the ones here are fine for testing but were not generated with a CSPRNG.

How to use

1. Choose how many UUIDs you want.
2. Click Generate to produce version 4 UUIDs.
3. Copy them into your code or data.
4. Generate more whenever you need them.

Use Cases

• •Seeding a database with primary keys
• •Generating IDs for test fixtures
• •Building mock API payloads
• •Creating request or correlation IDs
• •Filling identifier fields in sample data

Tips

• →Use them freely for tests and seed data.
• →Generate production IDs in your own runtime.
• →They never need central coordination.
• →Copy a batch at once to save time.

FAQ