Universally unique identifiers ('UUIDs') can be sub-optimal for many uses-cases because they are not the most character efficient way of encoding 128 bits of randomness; v1/v2 versions are impractical in many environments, as they require access to a unique, stable MAC address; v3/v5 versions require a unique seed and produce randomly distributed IDs, which can cause fragmentation in many data structures; v4 provides no other information than randomness which can cause fragmentation in many data structures. Providing an alternative, 'ULIDs' have 128-bit compatibility with 'UUID', 1.21e+24 unique 'ULIDs' per millisecond, support standard (text) sorting, canonically encoded as a 26 character string, as opposed to the 36 character 'UUID', use 'base32' encoding for better efficiency and readability (5 bits per character), are case insensitive, have no special characters (i.e. are 'URL' safe) and have a monotonic sort order (correctly detects and handles the same millisecond).