ExNip Elixir library for NIP number. ExNip.valid?/1 - you can check if NIP number is valid More about NIP number: Wikipedia PL Usage iex> ExNip.valid?("1060000062") true iex> ExNip.valid?("106-00-00-062") true iex> ExNip.valid?("106-000-00-62") true iex> ExNip.valid?("1234567890") false Installation Package can be installed by adding ex_nip to your list of dependencies in mix.exs: def deps do [ {:ex_nip, "~> 0.1.0"} ] end Documentation Docs can be found at https://hexdocs.pm/ex_nip. License Source code of ex_nip is released under the Apache 2.0 license, see the LICENSE file.