UUID Generator
EncodingProcessed locally in your browser using the Web Crypto API. Nothing is sent to any server.
How It Works
This tool generates UUID v4 and UUID v7 identifiers using the Web Crypto API for cryptographically secure randomness.
UUID v4 — Random
- 16 random bytes with version (4) and variant (10xx) bits set
- 122 bits of randomness — collision probability is negligible
- Format:
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
UUID v7 — Time-ordered
- 48-bit Unix timestamp (milliseconds) + 74 bits of randomness
- Sort-friendly: lexicographic order matches chronological order
- Format:
xxxxxxxx-xxxx-7xxx-yxxx-xxxxxxxxxxxx - Defined in RFC 9562 (2024)
Use Cases
UUID v7 is ideal for database primary keys (B-tree friendly). UUID v4 is the classic choice when ordering doesn't matter. Both are globally unique without coordination.
Frequently Asked Questions
What is the difference between UUID v4 and v7?
UUID v4 is purely random (122 bits of entropy) and has no ordering. UUID v7 embeds a 48-bit Unix timestamp in the first bits, making it sortable by creation time while still providing 74 bits of randomness. Use v7 for database primary keys and v4 when ordering doesn't matter.
Are these UUIDs generated client-side?
Yes. All UUIDs are generated locally in your browser using the Web Crypto API. No data is sent to any server.
Is UUID v7 a standard?
UUID v7 is defined in RFC 9562 (published May 2024), which also covers UUID v6 and v8. It was designed as a modern replacement for v4 in systems that benefit from time-ordered identifiers.
Privacy Note
This tool runs entirely in your browser. Your input is never uploaded, stored, or sent to any server.
Disclaimer: This tool is provided for educational and informational purposes only. The results do not constitute professional security advice. Use at your own discretion.