UUID Generator
Generate cryptographically secure UUID v4 identifiers for your application.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used for information in computer systems. UUID v4, which this tool generates, uses random numbers to ensure uniqueness. The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where each x is a random hex digit. The probability of generating a duplicate UUID is astronomically small — making them practical for globally unique IDs without coordination between systems.
Common Use Cases
Database Primary Keys
Using UUIDs as primary keys enables distributed ID generation without a central authority or database sequence.
API Resource Identifiers
Expose resource IDs in REST APIs without leaking sequential internal IDs or database structure.
Session & Token IDs
Generate unique session tokens, CSRF tokens, and one-time-use codes for authentication flows.
File & Asset Names
Name uploaded files with UUIDs to avoid conflicts and obscure original filenames.
Distributed Systems
Microservices and distributed databases use UUIDs to generate unique IDs without inter-service coordination.
Event Sourcing
Assign unique IDs to events in event-sourced architectures for idempotency and deduplication.
FAQ
How unique are UUID v4 values?
UUID v4 has 122 bits of randomness, giving 5.3 × 10³⁶ possible values. The probability of generating a duplicate is so small it's effectively impossible in practice.
Are these UUIDs generated securely?
Yes — this tool uses the browser's crypto.randomUUID() API (or crypto.getRandomValues() as fallback) which produces cryptographically secure random values.
What's the difference between UUID versions?
UUID v1 is time-based, v3/v5 are name-based (deterministic), and v4 is random. v4 is the most commonly used for general-purpose unique IDs.
Should I store UUIDs as strings or binary?
Binary (16 bytes) is more efficient for storage and indexing in databases. String form (36 chars with hyphens) is convenient for display and APIs.