UUID Generator
Generate random UUIDs (v4) instantly. Multiple formats and bulk generation supported.
About UUID v4
UUID v4 uses random numbers. The probability of generating a duplicate UUID is extremely low (1 in 5.3×10^36). UUIDs are commonly used for database primary keys, session IDs, and unique identifiers.
Generate random UUID v4 identifiers for your applications. Generate multiple UUIDs at once, choose format options, and copy with one click. All generated client-side.
A UUID (universally unique identifier) is a 128-bit value that lets distributed systems mint IDs independently without coordinating with a central database. Version 4 UUIDs — the most common flavor — use 122 random bits, giving a collision probability so low you'd have to generate a billion IDs per second for about 85 years before the odds of a duplicate approach one in a billion. That's why they're the default for request IDs, idempotency keys, session tokens, and primary keys in systems that can't afford a round-trip to a sequence generator.
This tool uses the browser's crypto.getRandomValues() API, which is a cryptographically secure random source — not Math.random(), which is biased and predictable. Generated UUIDs follow RFC 4122, with the version nibble set to 4 and the variant bits set correctly so any spec-compliant parser accepts them. Bulk generation is supported: request one to a few thousand UUIDs at once for seeding a test database or pre-generating keys.
Typical scenarios include creating primary keys for new rows, generating idempotency keys for API retries, minting request-correlation IDs for distributed tracing, seeding stable fixture data in tests, and creating unique filenames for uploaded assets. Output is shown in the canonical 8-4-4-4-12 hexadecimal format with lowercase letters, with options for uppercase or stripped hyphens if your target format differs.
- 1
Set the quantity
Choose how many UUIDs you need — one for a quick test, or a few hundred for seeding a database. The default is one.
- 2
Generate
Click once and cryptographically random v4 UUIDs appear, each on its own line. Every UUID is independent so no sequencing or state is involved.
- 3
Copy or adjust format
Copy the full list to clipboard, or toggle uppercase and hyphen-stripping if your target system expects a different format.
Database primary keys
Generate UUIDs for new rows in PostgreSQL, MongoDB, or DynamoDB — especially useful when clients need to mint IDs offline before syncing.
API idempotency keys
Create unique keys for Stripe, Shopify, and other APIs that use idempotency headers to make retries safe.
Distributed tracing IDs
Mint request IDs and correlation IDs for logs so you can trace a single request across microservices.
Test fixture seeding
Generate stable-looking IDs for unit tests and integration fixtures when you need unique values but don't want to depend on a live DB.
Are these UUIDs cryptographically secure?
Yes. Generation uses crypto.getRandomValues(), the Web Crypto API's CSPRNG, not Math.random(). The random bits are suitable for security-sensitive uses like session tokens.
Can two UUIDs collide?
In theory yes, in practice no. With 122 random bits, you'd need to generate roughly 2.71 quintillion UUIDs before the probability of one collision reaches 50%. For any realistic workload, treat them as unique.
What version of UUID is generated?
Version 4 — random. If you need UUIDv7 (time-ordered, better for database indexes) or UUIDv1 (MAC-address based), use a library; most systems accept v4 without issue.
Is my generated UUID sent anywhere?
No. All randomness comes from your browser. Nothing is logged, stored, or transmitted. Refreshing the page discards them.
Can I generate UUIDs in bulk?
Yes. Request up to several thousand at a time for seeding test data or pre-generating keys. Larger bulk generation may slow your browser but won't fail.