UUID Generator
Generate cryptographically-random RFC 4122 v4 UUIDs in bulk.
About UUID Generator
The UUID Generator produces RFC 4122 version-4 UUIDs — 128-bit random identifiers used for primary keys, request IDs and correlation IDs. Generate one at a click or a batch of hundreds for seed scripts and test fixtures.
A version-4 UUID has a standardized hexadecimal layout with version and variant bits plus 122 random bits. It can be generated independently by browsers, services and databases without coordinating a central counter, which is why it is common in distributed systems.
Generation uses the browser's cryptographic random source (Web Crypto API), so IDs never pass through a server. Formatting options let you match dashed, dash-less, upper or lower conventions your codebase expects.
How UUID Generator works in practice
- 1Choose how many UUIDs you need.
- 2Pick formatting options: with or without dashes, uppercase or lowercase.
- 3Click "Generate".
- 4Copy the whole list with one click or download it as a file.
Jobs this tool is built for
- Create IDs for database seed rows before importing a fixture file.
- Assign correlation identifiers to sample requests used in distributed tracing tests.
- Populate stable-looking identifiers in UI mock data without exposing production records.
- Generate a batch of keys for offline scripts that cannot rely on an auto-incrementing database.
What you can do here
- RFC 4122 version-4 (random) UUIDs
- Batch generation for seed data and fixtures
- Uppercase, lowercase and dash-less variants
- Cryptographically secure random source
- Copy all or download as a file
Limits and honest caveats
- Version 4 UUIDs are randomly generated. Collisions are astronomically unlikely but not mathematically impossible.
- A UUID is an identifier, not a secret — it is not meant to be used as a password or security token.
- IDs are generated locally in your browser and are not logged or stored anywhere.
Common questions about UUID Generator
Are the UUIDs really unique?
Version 4 UUIDs contain 122 random bits, so the collision probability is negligible for any real-world use.
Can I generate time-based UUIDs (v1/v7)?
Only v4 is currently supported.
Should UUIDs be stored as text or binary?
That depends on the database. Text is easy to inspect, while a native UUID type or 16-byte binary representation usually uses less space and can index more efficiently.
Are uppercase and dash-less values still the same UUID?
Yes. Case and hyphen presentation do not change the underlying 128-bit value, though receiving systems may require the conventional dashed form.
This page was written by the ToolSink team to explain how UUID Generator works on this site — it is not syndicated, scraped, or spun from another publisher. How we write tool guides · Site updates · About ToolSink.
All Developer Tools
Tap any tool to jump straight in — no signup, works on mobile.