Question 1

What is a UUID and why should I use one?

Accepted Answer

A UUID (Universally Unique Identifier) is a 128-bit number that's practically guaranteed to be unique across all systems without central coordination. Use UUIDs when you need unique identifiers that can be generated independently by different systems, such as for database primary keys, API resources, session tokens, or distributed systems.

Question 2

Can two UUIDs ever be the same?

Accepted Answer

While theoretically possible, the probability is astronomically low. UUID v4 has 2^122 possible values (about 5.3 x 10^36). You would need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision. For practical purposes, UUIDs are unique.

Question 3

What's the difference between UUID versions?

Accepted Answer

UUID v1 uses timestamp and MAC address (reveals when/where created). UUID v4 uses random numbers (most common for general use). UUID v5 uses SHA-1 hashing of a namespace and name (deterministic). UUID v7 is time-ordered with randomness (great for database performance). This tool generates v4 UUIDs.

Question 4

Are UUIDs secure enough for sensitive data?

Accepted Answer

UUID v4 is cryptographically random and hard to guess, but UUIDs are identifiers, not security mechanisms. Don't rely solely on UUIDs being unguessable. Always implement proper authentication and authorization. For session tokens, use dedicated security libraries rather than plain UUIDs.

Question 5

How should I store UUIDs in a database?

Accepted Answer

Avoid storing UUIDs as VARCHAR(36). Instead, use your database's native UUID type (PostgreSQL, MySQL 8+) or store as BINARY(16). This saves storage (16 bytes vs 36), improves index performance, and speeds up queries. Many ORMs can handle the conversion automatically.

Question 6

Why do UUIDs have hyphens?

Accepted Answer

The 8-4-4-4-12 format with hyphens is the standard representation (RFC 4122). The hyphens separate the UUID into five groups for readability but serve no technical purpose. When storing in databases, you can remove hyphens to save space, but include them when displaying to users.

Question 7

uuidGenerator.faq.q7.question

Accepted Answer

uuidGenerator.faq.q7.answer

Question 8

uuidGenerator.faq.q8.question

Accepted Answer

uuidGenerator.faq.q8.answer

UUID Generator

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