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🆔 UUID Generator
Generate one or hundreds of RFC 4122 v4 UUIDs, cryptographically random.
0 UUIDs • RFC 4122 v4
Uses the browser crypto.randomUUID() (RFC 4122 v4 - cryptographically random).
How This Tool Works
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify resources in computing. UUIDs are designed to be globally unique without a central authority — the probability of generating a duplicate is so low (1 in 2^122 for v4) that for all practical purposes, every UUID ever generated is unique. They are used as database primary keys, session tokens, API request identifiers, file names, and anywhere you need a unique ID that will not collide with any other. This generator creates version 4 UUIDs using cryptographically secure randomness.
💡 Tips & Best Practices
- 1UUID v4 (random) is the most common type and is suitable for most applications.
- 2UUIDs are 36 characters long (32 hex digits + 4 hyphens), e.g., 550e8400-e29b-41d4-a716-446655440000.
- 3For database primary keys, consider whether UUIDs or auto-incrementing integers are more appropriate — UUIDs prevent ID guessing but are larger (16 bytes vs 4–8 bytes).
- 4Never use UUIDs as security tokens — while they are unique, v4 UUIDs are not cryptographic secrets.
Frequently Asked Questions
What are the different UUID versions?
V1 uses timestamp + MAC address (reveals machine info). V3 and V5 are namespace-based (deterministic). V4 is purely random (most common). V7 is time-ordered random (good for database primary keys that need to sort chronologically). This generator creates V4 UUIDs.
Can two UUIDs ever be the same?
Theoretically yes, but practically no. A v4 UUID has 122 random bits, giving 5.3 × 10^36 possible values. You would need to generate 1 billion UUIDs per second for 100 years to have a 50% chance of a single duplicate.
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