7 min read · Try UUID Generator
Why UUID v4 for public IDs
Random v4 IDs are hard to guess compared to sequential integers—useful for public resource URLs when authorization still guards access. They spread writes in some database indexes better than auto-increment.
Collision reality
Collision probability is negligible at application scale if you use a proper RNG. Still use unique constraints in the database—defense in depth beats theoretical arguments.
v4 vs v7
UUID v7 (time-ordered) improves index locality for high-insert tables. v4 remains the default for opaque tokens; choose v7 when sortable creation time helps operations.
Logging and support
Log full UUIDs in support tools; truncating IDs in user-facing errors is fine if internal tools can look up the complete value.
This article is part of the DevToolsHub learning guides—original writing meant to complement our free tools, not replace official documentation from vendors or standards bodies.