How does NanoID compare to UUID v4 in size?

A 21-character NanoID has the same collision probability as UUID v4 but is 36% shorter.

What is the default NanoID alphabet?

The default URL-safe alphabet is A-Za-z0-9_- (64 characters), producing 21-char IDs with 126 bits of entropy.

Yes. Set the alphabet to 0-9 for a pure-numeric ID, though you will need a longer length for the same entropy.

Yes. It uses crypto.getRandomValues for secure random bytes on every generation.

Configure alphabet and length to generate NanoID strings shorter and URL-safer than UUIDs.

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Configure alphabet and length to generate NanoID strings shorter and URL-safer than UUIDs.

Last updated: 2026-06-09 · Reviewed by Nham Vu