What is UUID v4?
UUID v4 is the most widely used version of the Universally Unique Identifier standard. Unlike other versions that use timestamps or hardware MAC addresses, v4 is generated using cryptographically strong random numbers. Out of the 128 bits in the ID, 122 bits are purely random, making the probability of a collision virtually zero.
Character Layout
| Segment | Characters | Description |
|---|---|---|
| Random Part 1 | f47ac10b-58cc |
The first 48 bits of pure random data. |
| Version | 4 |
Fixed at 4 to identify it as a random UUID. |
| Random Part 2 | 372 |
12 more bits of random data. |
| Variant | a |
Fixed at 8, 9, a, or b (RFC 4122). |
| Random Part 3 | 567-0e02b2c3d479 |
The final 62 bits of random data. |
Key Advantages
- 🕵️ Total Randomness: No embedded timestamps; impossible to tell when or where it was generated.
- 🌌 High Collision Resistance: $2^{122}$ combinations allow billions of IDs every second without duplicates.
- 🔌 Stateless Generation: Does not require system clock sync, making it highly portable.
- 🌍 Universal Support: Native support in almost every modern programming language.
How to Use
- Batch Selection: Choose how many random IDs you need.
- Generate: Our server uses a secure entropy source for 122 random bits.
- Deploy: Copy and use as tokens, API keys, or primary keys.
Frequently Asked Questions
Use v4 when you don't want people to know the creation order. It is better for security tokens or password reset links where anonymity is key.
Yes. Because it uses cryptographically secure randomness, UUID v4 is considered "unguessable" and safe for public-facing secure identifiers.
No. Since v4 has no timestamp data, it cannot be converted to a time-sortable v7. They serve different architectural purposes.
While UUID v4 is great for privacy, UUID v7 is better for database indexing and performance.