UUID Generator
Bulk UUID v4 & time-ordered v7 (RFC 9562), client-side
What Is a UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit value used to label database rows, API resources, session tokens, and events so that any machine can generate identifiers independently without collisions. This generator produces two versions: v4, which is fully random, and v7, which is time-ordered per RFC 9562 and plays better with database indexes because new values sort naturally. It can generate up to 100 UUIDs at once, in uppercase or without hyphens, and you can copy the whole list or download it as a text file. Generation uses the Web Crypto API right in your browser — no server round trip. Developers, backend engineers, and anyone seeding databases or mocking API responses will find it useful.
What this tool can do
- 🎲 v4: cryptographically random UUIDs from Web Crypto
- 🕰️ v7: time-ordered UUIDs per RFC 9562, friendly to database indexes
- 📦 Bulk generation: 1 to 100 identifiers in one click
- 🔠 Uppercase or lowercase output
- ✂️ Optional no-hyphen form, 32 hex characters
- 📥 Copy all results or download them as uuids.txt
When you will use it
- Seeding primary keys for a new database schema
- Generating realistic test fixtures for API clients
- Creating idempotency keys for payment calls
- Producing client-side identifiers for offline-first apps
Privacy: every UUID is generated locally with Web Crypto — nothing is sent over the network and nothing is logged. Free and registration-free.
Version and variant bits, demystified
A UUID looks like random noise, but 128 bits carry self-describing metadata:
- The version nibble identifies the recipe — this tool generates v4: 122 truly random bits plus six version/variant marker bits.
- The variant bits lock the layout to the RFC 9562 “Leach–Salz” form every mainstream library expects.
- Newer v7 UUIDs encode a timestamp so they sort naturally in database indexes; v4 values scatter, which is fine for keys but useless for ordering.
Not all UUIDs are alike
v4 or time-ordered v7
Generate v4 UUIDs from pure randomness, or v7 identifiers whose timestamp prefix sorts naturally and plays better with database indexes under RFC 9562.
Bulk up to 100
Request anywhere from 1 to 100 identifiers in a single run, then copy the whole list or download it as a text file for seeding fixtures and test data.
Casing and hyphen control
Uppercase output suits systems that expect capital identifiers, and the no-hyphen option produces plain 32-character strings that fit legacy columns without post-processing.
Bulk generation, honestly bounded
Up to 500 at once — uniqueness comes from the 122-bit space itself, not from checking a list.
Frequently asked questions
UUID v4 vs v7 — which should I use?⌄
v4 is fully random and is the safe default. v7 embeds a millisecond timestamp in the high bits, so values sort by creation time — ideal as database primary keys because inserts stay index-friendly. Both are standardized in RFC 9562.
Can generated UUIDs collide?⌄
v4 has 122 random bits: you would need to generate about 2.7×10¹⁸ UUIDs for a 50% chance of a single collision. For practical purposes, collisions do not happen.
Are these UUIDs generated on your server?⌄
No — everything runs in your browser with crypto.randomUUID() and crypto.getRandomValues(). The list is never transmitted anywhere.
Can a UUID reveal when or where it was created?⌄
A v1 UUID can: it embeds a timestamp and frequently the MAC address of the machine that made it — a genuine privacy leak. The v4 UUIDs this tool produces carry no such information; there is nothing to reverse.