UUID Generator
Generate cryptographically secure UUID v4 and UUID v7 identifiers in bulk — perfect for testing and database seeding.
Options
Random — 122 bits of entropy.
10 UUIDs
97e884a1-e3e8-4035-b848-756b03cef208d2b15008-6199-45f7-b4d1-ad084e71539144294a64-19ea-43fe-98c2-e16431709d0cc9604cb1-88eb-46b1-a376-3ee60c618422414a04ea-778f-424b-b9ac-1cd68a5ffd8b2fac56cd-abd9-4523-b6be-b59d7abc426801f83327-edb1-41a7-af99-3d2c8776487df9548213-2438-4d0f-9faf-bbf559a5bac8a4dffb3b-7681-47e0-849d-3d2880e5539642ba06c2-f198-4bc1-b060-4aa068420d00About this tool
A free UUID generator that produces UUID v4 (random) and UUID v7 (time-ordered) identifiers using your browser's crypto.getRandomValues API. Generate up to 100 at once, with options for uppercase output or removing dashes.
How to use it
Quick steps to get the most out of this utility.
- 1
Pick a version
UUID v4 for general use (random). UUID v7 if you need natural time ordering for database primary keys.
- 2
Choose count
The slider goes from 1 to 100. Useful for seeding test data or generating many keys at once.
- 3
Toggle formatting
Uppercase or remove dashes if your platform expects a specific format.
- 4
Copy
Each UUID has its own copy button. Use Copy All to grab the entire list at once.
UUIDs in the real world
A UUID (Universally Unique Identifier) is a 128-bit value designed to be unique across space and time without needing a central authority. The defining feature is that you can generate one on any machine, right now, with no coordination — and it'll still be unique.
Use UUIDs when you need identifiers that won't collide across systems: distributed databases, public APIs, file uploads, event sourcing. Use auto-incrementing integers when you control the database centrally and don't need cross-system uniqueness — they're smaller and faster.
Choosing v4 vs v7
- UUID v4: use it for security-sensitive identifiers (session tokens, API keys) where unpredictability matters.
- UUID v7: use it for database primary keys, event IDs, and any case where time ordering helps performance or debugging.
- Both versions are unique; v7's only “weakness” is that the timestamp prefix is mildly inferable — usually a non-issue.
Frequently asked questions
What's the difference between UUID v4 and UUID v7?+
UUID v4 is fully random — perfect when you need unpredictability and don't care about ordering. UUID v7 starts with a millisecond timestamp, so identifiers generated later sort after earlier ones. v7 is increasingly recommended for database primary keys because it preserves index locality.
Are UUIDs really unique?+
For UUID v4, the chance of collision is astronomically small. You'd need to generate billions of UUIDs per second for many years to have a meaningful probability of duplication. In practice, treat them as unique.
Can I use UUIDs as database primary keys?+
Yes, but be aware of trade-offs. UUID v4's randomness causes B-tree index fragmentation in some databases. UUID v7's time-ordered design avoids this. Both UUIDs are 16 bytes vs 4 or 8 for an integer, so storage and index size are larger.
Is this generator cryptographically secure?+
Yes. The tool uses crypto.randomUUID and crypto.getRandomValues, which are backed by your operating system's secure random number generator. Output is suitable for security-sensitive use cases like session tokens.
What is the 'nil' UUID?+
The nil UUID is a special all-zeros value (00000000-0000-0000-0000-000000000000). It's defined in the UUID spec as a placeholder representing 'no UUID', commonly used as a default or sentinel value in databases.
Keep exploring
More utilities and reading from Toolisk.