How to use UUID, ULID and NanoID Generator and Validator

Choose Generate new identifiers or Check the format of an identifier.
Pick a Format: UUID version 4 or 7, ULID or NanoID.
Set How many to generate, and for NanoID the length and alphabet.
Select Generate the identifiers, or paste a value to check.

Example: UUID, ULID and NanoID Generator and Validator

Generate three version 4 UUIDs.

You add

What do you want to do: Generate new identifiers. Format: UUID version 4. How many to generate: 3.

You get

The result reports Generated 3 uuid-v4 values. Each value is 36 characters in the 8-4-4-4-12 layout, with 4 in the version position and 8, 9, a or b in the variant position.

Options

Format: UUID version 4 is random. UUID version 7 and ULID put a millisecond timestamp first, so a sorted list follows creation time. NanoID is short and uses the alphabet you set.
NanoID length and alphabet: Length runs 6 to 64, with 21 as the default. Every alphabet character must be unique, and at least two are needed. Bytes that would bias the first characters are skipped.
Identifier to check: Used by the check action. The format is detected from the value, and a NanoID check also uses the length and alphabet you set.

Supported inputs and limits

1 to 200 identifiers per run. Four formats are supported. NanoID length runs from 6 to 64, and a repeated alphabet character is refused because it raises the chance of a clash. Random values come from the browser's secure generator, and generation stops if that generator is not available. UUID version 7 and ULID carry a millisecond timestamp, so two values made in the same millisecond may not sort in creation order. A format check reads the shape only and cannot prove uniqueness, origin or secrecy.

Where your input is processed

This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Four identifier shapes

UUID version 4 holds 122 random bits, so a collision is unlikely but nothing is ordered. UUID version 7 and ULID both begin with a millisecond timestamp, which makes them useful as database keys, though values from the same millisecond still need a tie-breaker. NanoID drops the structure and trades it for a short string from an alphabet you choose.

RFC 9562, Universally Unique Identifiers

Questions about UUID, ULID and NanoID Generator and Validator

Does a passing format check mean the value is genuine?

No. The check reads length, separators, version and variant bits or the alphabet. A value typed by hand can match that shape, so nothing here says who made it or whether it is unique.

Can I use these values as passwords or API keys?

No. An identifier names a record; it does not guard one. Use a password or token generator for secrets, and keep the server-side controls that go with them.

Why do two UUID version 7 values not sort by time?

Values made in the same millisecond share a timestamp prefix, and the rest is random, so their order inside that millisecond is arbitrary. The tool calls this time-prefixed order, not a sequence.

What are the NanoID defaults?

21 characters from a 64-character alphabet, which matches the NanoID default. You can set 6 to 64, and the check follows the length you set.

Project manager: Tony Hines · Content updated 29 September 2026 · Report a problem

UUID, ULID and NanoID Generator and Validator

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