UUID Generator
Generate UUID v4 identifiers instantly. Perfect for database keys, testing, and software development.
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Frequently Asked Questions
What is a UUID and what is it used for?
UUID (Universally Unique Identifier) is a 128-bit label formatted as a 36-character string. It provides unique identifiers across systems without central coordination. Common uses include database primary keys, session IDs, API tokens, and distributed system identifiers.
What is the difference between UUID v1, v4, and v7?
UUID v1 uses timestamp and MAC address for time-ordered IDs but exposes privacy information. UUID v4 uses cryptographically secure random numbers for maximum entropy and privacy. UUID v7 combines time ordering with random bits for sortable IDs without privacy concerns.
How unique are UUID v4 identifiers?
UUID v4 uses 122 random bits, providing approximately 2^122 unique values (about 5.3 x 10^36). The probability of generating the same UUID twice is negligible, making collisions essentially impossible in practice. This makes v4 ideal for most general-purpose applications.
Should I use UUIDs as primary keys in databases?
UUIDs work as primary keys but have tradeoffs. They provide global uniqueness and security (no enumeration attacks), but are larger, slower for indexing, and can cause database fragmentation. For most applications, a sequential integer or UUID v7 is more efficient for indexing.
Is my data sent to a server?
No. All UUID generation uses cryptographically secure random number generation locally in your browser. Generated UUIDs never leave your device and are not stored or transmitted to any server.
What format is a UUID v4 in?
A UUID v4 has the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is any hex digit and y is 8, 9, a, or b. The 4 indicates version 4, and the variant bits are set to conform to the RFC 4122 standard for distributed unique identifiers.