Nano ID generator

Nano ID is a tiny, secure, URL-friendly unique ID format. A default Nano ID looks like V1StGXR8_Z5jdHi6B-myT: 21 characters from a 64-symbol alphabet of letters, digits, underscore and hyphen. It is a popular alternative to UUIDs for database keys, short links, file names and API resource IDs because it is shorter and needs no escaping in URLs.

How to use it

1. Choose the number of IDs to generate.
2. Set the length and, optionally, a custom alphabet.
3. Copy the IDs.

How strong are Nano IDs?

Each character from the default 64-symbol alphabet carries 6 bits of randomness, so 21 characters give 126 bits, comparable to a UUID v4 (122 bits). IDs are generated with a cryptographically secure random source, so they are unpredictable.

Choosing a length

Shorter IDs are friendlier but collide sooner. With the default alphabet:

• 21 characters: you would need to generate about a billion IDs per second for many thousands of years to reach a 1% collision chance.
• 10 characters (60 bits): about 1 billion IDs gives roughly a 1 in 2,300 collision chance.
• 8 characters (48 bits): collisions become likely after millions of IDs.

Custom alphabets

• Use 0123456789abcdefghijklmnopqrstuvwxyz for case-insensitive systems.
• Remove look-alike characters such as 0, O, 1, l and I for codes people type by hand.
• A smaller alphabet carries fewer bits per character, so increase the length to compensate.

Nano ID vs. UUID vs. ULID

Use UUID when a standard format is required, ULID or UUID v7 when IDs must sort by creation time, and Nano ID for short, URL-safe random IDs.