To start the server you need these environment variables set in config/secrets.yml:

• app_id - Your application id/uid
• app_secret - Your application secret
• app_access_token - Your application access token (that allows you to create new users) please read further on how to obtain it

Register you application in Boleto Simples at https://sandbox.boletosimples.com.br/conta/api/aplicacoes

Check lib/get_access_token.rb

require "boletosimples"

BoletoSimples.configure do |c|
  c.environment = :sandbox
  c.application_id = "app_id"
  c.application_secret = "app_secret"
end

puts BoletoSimples.configuration.client_credentials