UUID Generator
Generate random UUIDs (Universally Unique Identifiers) version 4. Create single or bulk UUIDs instantly.
Preview Format
a1b2c3d4-e5f6-4890-a234-567890123456A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. This generator creates version 4 UUIDs which are randomly generated using cryptographically secure random numbers.
UUID v4 has become the most widely used UUID version due to its simplicity and excellent uniqueness properties. The probability of generating a duplicate is so low that for practical purposes, each UUID can be considered unique.
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxxStructure
- 8-4-4-4-12 hexadecimal digits
- Total: 32 hex characters (36 with dashes)
- 128 bits of data
Version Indicators
- 4 in position 13 = version 4
- y is 8, 9, a, or b (variant bits)
- x = any hexadecimal digit (0-f)
Database Primary Keys
Unique identifiers that don't reveal record count or creation order
Session Identifiers
Secure, unpredictable tokens for user sessions
API Request Tracking
Trace requests across distributed systems
Transaction IDs
Unique identifiers for financial or business transactions
File Naming
Prevent naming collisions for uploaded files
Distributed Systems
Generate IDs without coordination between servers
Bulk Generation
Generate up to 1000 UUIDs at once
Format Options
Choose uppercase and with/without dashes
Instant Generation
UUIDs generated immediately in your browser
Copy & Download
Copy all UUIDs or download as a text file
Preview Format
See the exact format before generating
100% Client-side
No server requests - all processing in browser
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. Version 4 UUIDs are randomly generated and have a very low probability of collision, making them ideal for distributed systems.
What is UUID version 4?
UUID v4 is randomly generated using random or pseudo-random numbers. The '4' in position 13 indicates the version, and positions 17-20 contain variant bits. The format is: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.
Are UUIDs truly unique?
While not mathematically impossible, the probability of generating duplicate UUID v4s is astronomically low (about 1 in 2^122). In practice, they can be considered unique for all real-world applications.
Should I use dashes in UUIDs?
The standard UUID format includes dashes (8-4-4-4-12), but many systems accept UUIDs without dashes. Both formats represent the same 128-bit value. Use the format that your system expects or that's easier to work with.
UUID vs GUID - what's the difference?
UUID and GUID (Globally Unique Identifier) are essentially the same thing. GUID is Microsoft's term, while UUID is the standard term used in RFC 4122. They follow the same format and generation algorithms.
Can I use UUIDs as database primary keys?
Yes, UUIDs are commonly used as primary keys. They offer benefits like no coordination needed for ID generation and no information leakage. However, they take more storage space than integers and can impact index performance.
Are these UUIDs cryptographically secure?
This generator uses JavaScript's Math.random() which is not cryptographically secure. For security-critical applications (like session tokens), use crypto.randomUUID() or a server-side cryptographically secure generator.