Keysmith - a library for generating unique IDs

eproxus
Wed, 01 Apr 2026 08:38:38 +0000
Libraries

This library has been in production use for a while, but I wanted to post it here in case anyone else finds it useful

Keysmith

KeySmith is a library for generating unique IDs. It supports two types of
IDs:

UUID (RFC-9562)

The ‘nil’ uuid (00000000-0000-0000-0000-000000000000)

The ‘max’ uuid (ffffffff-ffff-ffff-ffff-ffffffffffff)

Version 4 (random)

Version 7 (time-based and random)

TypeID (specification)

TypeID’s embed a UUID v7 by default, but can be customized with any
supported UUID version

Keysmith is a well tested, secure and performant:

Full test coverage

Property-based tests

Uses crypto for secure random number generation

Fast and efficient using binary pattern matching

Usage

KeySmith provides functions to generate UUIDs and TypeIDs. Here are some basic
examples:

Generating UUIDs

You can generate UUIDs version 4 (random) and version 7 (time-based):

% Generate a UUID v4
1> keysmith:uuid(4).
<<"79782daf-ff7d-4426-a8f5-e12672e89e32">>

% Generate a UUID v7
2> keysmith:uuid(7).
<<"01922919-44d3-779c-84ad-20ab20fc7dbb">>

% Generate a UUID v7 with a specific timestamp
3> keysmith:uuid({7, 1234567890}).
<<"00004996-02d2-7bf9-9b68-599f55d37931">>

UUIDs can be generated in different formats:

4> keysmith:uuid(4, binary).
<<193,169,209,27,160,43,73,83,147,64,63,136,127,77,166,39>>

5> keysmith:uuid(4, hex_nodash).
<<"01922919d63d7de990a0209e23b50747">>

Generating TypeIDs

TypeIDs are a combination of a type prefix and a UUID. They are useful for
creating namespaced unique identifiers:

% Generate a TypeID with default UUID v7
6> keysmith:type_id(user).
<<"user_01j8mhm5vafn8vprb7g6dz4q90">>

% Generate a TypeID with a specific UUID
7> keysmith:type_id(product, 4).
<<"product_7fv003jbwg9ptvecwr68p6n5k6">>

Parsing IDs

KeySmith can also parse UUIDs and TypeIDs back into their components:

8> UUID = keysmith:uuid(7).
<<"019228d7-b720-7484-ab83-25332e9b0a33">>
9> keysmith:parse(uuid, UUID).
#{var => rfc,
  ver => 7,
  bin => <<1,146,40,215,183,32,116,132,171,131,37,51,46,155,10,51>>,
  hex => <<"019228d7-b720-7484-ab83-25332e9b0a33">>,
  val =>
      #{rand_a => <<72,4:4>>,
        rand_b => <<174,12,148,204,186,108,40,51:6>>,
        unix_ts => {millisecond,1727262078752}}}

10> TypeID = keysmith:type_id(order).
<<"order_01j9p6jwxyfzjawx1ksjyzp9gy">>
11> keysmith:parse(type_id, TypeID).
{type_id,order,
         #{var => rfc,
           ver => 7,
           bin => <<1,146,108,105,115,190,127,228,174,116,51,204,189,251,38,30>>,
           hex => <<"01926c69-73be-7fe4-ae74-33ccbdfb261e">>,
           val =>
               #{rand_a => <<254,4:4>>,
                 rand_b => <<185,208,207,50,247,236,152,30:6>>,
                 unix_ts => {millisecond,1728395703230}}}}

For more detailed information on available functions and options, please refer
to the module documentation.

Links

You can find Keysmith here:

Hex

Documentation

GitHub

github.com

GitHub - eproxus/keysmith: A Erlang library for generating unique identifiers

A Erlang library for generating unique identifiers

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