UUID Generator
Generate UUID v4 (random), v7 (time-ordered), and v5 (namespace + name, SHA-1) in bulk, plus v3 (namespace + name, MD5) for legacy interop, using your browser's cryptographic randomness. Choose an output format, dedupe, and sort. The Decode / inspect tab reads a pasted UUID's version, variant, and (v7) timestamp; Collision odds estimates the birthday-paradox risk. Nothing is uploaded.
Auto-generates as you change options. Choose Generate UUIDs for a fresh set.
How to use the UUID Generator
Generate one or many UUIDs (UUID v4) at a time for test data, database seeds, API fixtures, primary keys, log correlation IDs, and migration scripts. Pick the format — standard lowercase with hyphens, uppercase, no-hyphens (32-char hex), or wrapped in braces — and download or copy in bulk. UUIDs are generated cryptographically in your browser; nothing is uploaded.
What it does
- Generates RFC 4122 UUID v4 values using
crypto.getRandomValues. - Bulk generation: up to hundreds at a time.
- Formats: standard (
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx), uppercase, no-hyphens (32 hex), or braces ({xxxxxxxx-...}). - Copy to clipboard, download as a text file, or hand off to CSV → SQL for inserts.
- Useful for any unique-ID requirement that does not need ordering or central allocation.
When to use it
- Seed a development or QA database with unique primary keys.
- Generate IDs for API test fixtures, snapshot tests, or Storybook stories.
- Create correlation IDs for log replay or load test runs.
- Produce idempotency keys for replayable API calls.
- Generate one-off external IDs in a migration script.
- Create namespace IDs for multi-tenant test scenarios.
How to use it
- Set the quantity — 1 for a single ID, more for bulk needs.
- Choose the format: hyphenated lowercase (most common), uppercase, no hyphens, or braces.
- Click Generate; copy or download the list.
Tips & pitfalls
- UUID v4 is the most portable variant — avoid v1 in test data because it can leak MAC and timestamp information.
- For database primary keys, use a native
UUIDcolumn type (PostgreSQL) orCHAR(36)/BINARY(16)rather thanVARCHAR(255). - UUIDs are not sequential — random UUIDs hurt B-tree index locality. Consider ULIDs or UUID v7 (time-ordered) for hot-path keys.
- Hyphen-free 32-char hex is required by some systems (e.g., AWS request IDs, GitHub OIDs) — confirm before generating in bulk.
- Do not use UUIDs as security tokens — they are unique, but not secret. Use the Token Generator for secrets.
FAQ
- What is UUID v4? A version of RFC 4122 where the bits are mostly random. It is the safest default for general unique-ID needs.
- Are UUIDs really unique? Practically, yes — the probability of collision is astronomically small. For everyday use, treat them as unique.
- How is this different from a GUID? GUID is Microsoft's term for the same concept. The format is interchangeable.
- Should I use UUID v4 or v7? v4 is fully random and most portable. v7 is time-ordered and friendlier to database indexes — choose v7 if your tooling supports it.
- Are generated UUIDs uploaded? No. Generation uses
crypto.getRandomValuesin your browser. - Can I use a UUID as a secret token? Not recommended — UUIDs are unique but not secret-strength. Use a cryptographically random token of 32+ characters.
Runs locally in your browser using crypto.getRandomValues. No uploads. UUIDs are unique IDs, not secrets — generate tokens with the Token Generator.