What is this tool?
Generate cryptographically random Universally Unique Identifiers (UUIDv4) directly in your browser. Configurable options include case formatting, hyphen delimiters, and batch size up to 50 identifiers.
When to use it?
Generate primary keys for databases (PostgreSQL, MySQL, SQLite), unique request IDs for distributed logging, transaction trace IDs, or random idempotency keys for API payloads.
How does it work?
Uses the browser Web Crypto API (crypto.getRandomValues) to fill a 16-byte buffer with hardware-derived cryptographically secure pseudorandom numbers (CSPRNG), sets the 4-bit version (0100) and 2-bit RFC 4122 variant (10xx), and formats the result as a 36-character hexadecimal string.
Technical Specifications & Standards
UUIDv4 contains 122 bits of random entropy out of 128 total bits. The probability of generating a duplicate identifier across billions of iterations is negligible (1 in 2^122).
Operating Limits & Considerations
- UUIDv4 is un-ordered and not time-sequential. If you need chronologically sortable identifiers, consider ULID or UUIDv7.
- Batch generation is capped in the interface at 50 per click to ensure zero UI thread latency.
Example Conversions
Count: 1, Format: Uppercase, Hyphens: Enabled
9B1DE2F8-0D32-475C-9A8B-3FA41829B245
Standards & Technical References
Frequently Asked Questions
A UUIDv4 is formatted as 32 hexadecimal digits displayed in five groups separated by hyphens (8-4-4-4-12). The 13th digit is always 4 (representing Version 4), and the 17th digit is 8, 9, A, or B (representing the RFC 4122 variant).
Yes. Because they are generated using cryptographically secure random values via the Web Crypto API, they provide 122 bits of collision resistance.