UUID Generator
Generate universally unique identifiers (UUIDs) locally in your browser. Supports UUID v4 (random) and v7 (time-ordered). No signup, no server upload — everything runs on your device.
Privacy note: UUIDs are generated locally using crypto.randomUUID() and crypto.getRandomValues(). Nothing leaves your browser.
UUID v4 vs UUID v7 — What's the difference?
| Version | Generation | Best for |
|---|---|---|
| v4 | 122 bits of randomness | Simple unique IDs, tokens, session keys |
| v7 | 48-bit timestamp + 74 random bits | Database primary keys, sorted inserts, event streams |
When should I use UUIDs?
- Database primary keys — v7 won the new standards vote for its sort-friendly timestamp prefix.
- API resource identifiers — UUIDs are globally unique and don't need centralized coordination.
- Transaction or order IDs — hard to guess and easy to generate in bulk.
- Anonymous event tracking — generate a one-time UUID per visitor action instead of using personal data.
Are UUID v7 really better for databases?
Put simply: yes, for most modern databases. UUID v4 values are scattered across the key space, which leads to B-tree page splits in Postgres/MySQL. UUID v7 starts with a timestamp, so new rows insert in roughly sequential order. The difference is noticeable at scale.
How this tool works
UUIDs are generated entirely in your browser using the Web Crypto API. No data is transmitted to TinyToolbox or any third party. Bulk generation (up to 100) creates each UUID independently from fresh random values, not from a seeded sequence.
Quick reference
A UUID is a 128-bit label. It looks like the display format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (36 characters including hyphens). The version digit is at position 14 — for v4 it's always 4, for v7 it's always 7. The variant bits at position 19 are always 8, 9, a, or b.
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