UUID Generator: Generate Unique Identifiers Online
Need a unique ID for your project? Our free online UUID generator creates universally unique identifiers instantly. A UUID (Universally Unique Identifier) is like a special code that's virtually guaranteed to be one-of-a-kind—perfect for labeling records in databases, tracking user sessions, or identifying files and documents.
Choose between UUID v4 (completely random) or UUID v1 (includes timestamp). Generate one UUID or hundreds at once. Everything runs securely in your browser—no data is sent to any server. Just click generate, copy, and use in your application.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. UUIDs are standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE).
UUID Versions:
Generated from random or pseudo-random numbers. This is the most commonly used version.
Example: 550e8400-e29b-41d4-a716-446655440000
Generated using the current timestamp and the MAC address of the computer.
Useful when you need to know when a UUID was created.
Example: 6ba7b810-9dad-11d1-80b4-00c04fd430c8
Common Use Cases:
- Database primary keys
- Session identifiers
- File and document identifiers
- Transaction IDs
- Distributed system identifiers
- API request tracking
Features:
- Cryptographically secure generation using Web Crypto API
- Support for UUID v4 (random) and v1 (timestamp-based)
- Multiple output formats (standard, uppercase, no-hyphens, braces)
- Bulk generation (up to 100 UUIDs at once)
- 100% client-side - no server communication
- Your UUIDs never leave your browser
UUID Format:
A standard UUID consists of 32 hexadecimal digits displayed in 5 groups separated by hyphens:
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
Where:
- M indicates the version (4 = random, 1 = timestamp)
- N indicates the variant (always 8, 9, A, or B)
Frequently Asked Questions
What is a UUID and why do I need one? +
A UUID (Universally Unique Identifier) is a 128-bit identifier that's virtually guaranteed to be unique across all systems worldwide. You need UUIDs when you want to identify records in databases, create unique session tokens, generate file names, or any situation where you need an ID that won't conflict with others—even across different servers or applications.
What's the difference between UUID v4 and UUID v1? +
UUID v4 is completely random, generated using cryptographically secure random numbers. UUID v1 includes a timestamp and your device's MAC address, making it sortable by time but potentially exposing some system information. For most use cases, UUID v4 is recommended as it's more private and still has virtually zero collision risk.
Can two UUIDs ever be the same? +
Theoretically yes, but practically no. UUID v4 has 122 random bits, giving 5.3 x 10^36 possible combinations. The probability of generating duplicate UUIDs is astronomically low—you'd need to generate 1 billion UUIDs per second for 100 years to have a 50% chance of a single collision.
Are UUIDs good for database primary keys? +
UUIDs work well as primary keys, especially in distributed systems where you can't coordinate ID generation. However, they're larger than auto-incrementing integers (16 bytes vs 4-8 bytes) and can impact index performance. Consider UUID v7 (time-ordered) for better database performance, or use UUIDs alongside auto-increment IDs.
What format should I use for my UUID? +
The standard format is 8-4-4-4-12 hexadecimal digits with hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). For URLs or compact storage, you can remove hyphens or use Base64 encoding. Our tool supports multiple formats including uppercase, no hyphens, and braces for different system requirements.