Dev
UUID v4 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
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Choose how many UUIDs you want.
- Click Generate to produce version 4 UUIDs.
- Copy them into your code or data.
- 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
what is a version 4 UUID
A version 4 UUID is a 128-bit identifier built mostly from random bits, with fixed version and variant markers. It is the most common UUID type because it needs no central coordination — you just generate one and the chance of a collision is negligible.
are these UUIDs RFC 4122 compliant
Yes. The generator fixes the version nibble to 4 and sets the variant bits to the RFC 4122 value, producing properly formatted 8-4-4-4-12 hyphenated hex strings that pass standard UUID validators.
can I use these in production
They are ideal for development, testing, and mock data. For production identifiers — especially anything security-sensitive — generate UUIDs from a cryptographically secure random source in your own application rather than reusing throwaway values copied from a tool.
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