ULID Generator

Easily generate unique IDs that can be sorted chronologically.





What is ULID Generator?

It is a simple tool to generate ULID (Universally Unique Lexicographically Sortable Identifier).

About ULID

A ULID is a unique identifier (ID) generated by combining time and randomness.
The following are points where ULID differ from UUID and the characteristics of ULID.

  • 128-bit compatibility with UUID
  • 1.21e+24 unique ULID per millisecond
  • Sortable by dictionary order
  • Normalized as a 26-character string, unlike 36-character UUID
  • Uses Base32 encoding for efficiency and readability (5 bits per character)
  • Case insensitive
  • No special characters (URL safe)
  • Monotonic sort order (correctly detects and processes identical milliseconds)

※ULID Specifications: https://github.com/ulid/spec

How to use the ULID Generator

  1. select the generation method
  2. enter the seed time to be used for generation

Click the Generate ULID button to generate ULIDs according to the specified configuration.
The number of ULIDs to be generated at one time can be specified, and the number can be changed from 1 to 100.

About the ULID Configuration


Generated by combining a timestamp with random bits generated by a cryptosecure pseudo-random number generation algorithm.

Time seed

Generate by specifying a seed time.
If the same seed time is used, the timestamp component (first 8 bytes) of the generated ULID will always be the same.
However, since the remaining 8 bytes of the ULID are random bits, different ULIDs are generated even if the timestamp component is the same.


Generates monotonically increasing ULID.
By specifying the same seed time, it generates a strictly ordered ULID with the least significant random bit incremented by 1.