UUID Generator
Generate unique identifiers (UUID v4)
Generator Settings
About UUIDs
- • UUID v4 uses random or pseudo-random numbers
- • Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
- • The 4 indicates version 4, y is 8, 9, A, or B
- • Extremely low probability of duplicates (1 in 5.3 x 10³⁶)
- • NIL UUID is all zeros, used as special null value
Understanding UUIDs
A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. UUIDs follow the format of 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. They are standardized by RFC 4122 and are widely used in software development.
Common Use Cases
- Database Primary Keys: UUIDs are ideal for distributed systems where multiple nodes need to generate unique IDs independently without coordination.
- Session Identifiers: Web applications use UUIDs for session tokens and CSRF tokens because they are practically impossible to guess.
- File Naming: Generate unique filenames for uploaded files to avoid collisions in storage systems.
- Message Queues: Assign unique identifiers to messages in distributed messaging systems for tracking and deduplication.
- API Resources: Use UUIDs as resource identifiers in RESTful APIs to prevent enumeration attacks (compared to sequential integer IDs).
UUID Version 4
This tool generates UUID v4 (random), which uses cryptographically strong random numbers. The probability of generating two identical UUID v4 values is astronomically low — you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of a collision. All generation happens locally in your browser using the Web Crypto API.