Are UUID v4 identifiers truly unique?

UUID v4 uses 122 random bits, giving 5.3 x 10^36 possible values. The chance of a collision after generating 1 billion UUIDs per second for 100 years is astronomically small.

What do the different UUID versions mean?

v1 uses timestamp and MAC address, v3 uses MD5 hash of a namespace, v4 uses random numbers, and v5 uses SHA-1 hash of a namespace. v4 is the most commonly used.

Should I use UUIDs as database primary keys?

UUIDs are great for distributed systems where coordination is difficult. However, their random nature can hurt B-tree index performance. Consider UUIDv7 (time-sorted) for better index locality.

// uuid-generator

UUID Generator

Generate random UUID v4 identifiers.

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How to Use UUID Generator

Set count-Choose how many UUIDs to generate (1 to 100).
Configure format-Toggle uppercase and hyphens options as needed.
Generate-Click Generate UUIDs to create new random identifiers.
Copy-Copy individual UUIDs or use Copy All for the entire list.

About UUID Generator

UUID (Universally Unique Identifier) v4 generates 128-bit random identifiers. The probability of a collision is so low that UUIDs can be generated independently without coordination.

UUIDs are widely used as primary keys in databases, session identifiers, correlation IDs in distributed systems, and unique file names.

Generated using the uuid library with crypto.getRandomValues for cryptographic randomness. All processing happens in your browser.

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