Overview
Generates version 4 UUIDs using the browser's own crypto.randomUUID(), so randomness comes from the platform cryptographic source rather than Math.random(). Produce up to 50 at a time and shape them for whatever field you are pasting into.
How It Works
Set a quantity between 1 and 50 and the list regenerates immediately. Two toggles change the format without changing the value: UPPERCASE for systems that expect hex in caps, and No dashes for the compact 32-character form that fits columns defined without hyphens. Each row has its own copy button, and Generate New replaces the whole batch.
Step-by-Step Usage Guide
- Set the quantity you need, up to 50 per batch.
- Toggle UPPERCASE or No dashes if the destination format requires it.
- Copy an individual value, or press Generate New for a fresh batch.
Technical Specifications & Standards
A v4 UUID is 122 bits of random data plus 6 fixed bits marking version and variant, which is why the 13th hex digit is always 4 and the 17th is one of 8, 9, a, or b. crypto.randomUUID() is required by specification to draw from a cryptographically strong source. That matters whenever identifiers must not be guessable, because Math.random() is seeded predictably in several engines and should never mint tokens or object ids.
Targeted Use Cases
- Seeding primary keys in test fixtures and database migrations.
- Creating correlation ids to trace one request across distributed service logs.
- Producing idempotency keys for payment or webhook retries.
- Naming storage objects or upload paths without coordinating a central counter.
Notes & Gotchas
- The dashed and undashed forms are the same identifier. Pick one per system and stay consistent, because string comparison across the two will fail.
- UUIDs are case-insensitive as identifiers but not as strings. Uppercase output is for display or legacy systems, not a different value.
- v4 UUIDs sort randomly. If you need ids that sort by creation time for index locality, UUIDv7 or ULID fits better.
- Stored as a native uuid type a UUID takes 16 bytes; stored as text it takes 36. On large tables that difference is worth caring about.
Frequently Asked Questions
Are these cryptographically random?
Yes. They come from crypto.randomUUID(), which the Web Crypto specification requires to use a cryptographically strong random source.
Are generated values sent to a server?
No. Generation happens entirely in your browser, so nobody else ever sees them, including this site.
Could I generate a duplicate?
Practically no. With 122 random bits you would need to generate billions per second for decades before collision probability became meaningful.
Why only 50 at a time?
It keeps the rendered list usable. For bulk generation call the same crypto.randomUUID() in your own code.