diff --git a/README.md b/README.md
index ffafdc7..a7b484e 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ config :shippex,
   currency: :usd, # :usd, :can, :mxn, :eur
   carriers: [
     ups: [
-      module: Shippex.Carrier.UPS,
+      module: Shippex.Carrier.UPS, # optional
       username: "MyUsername",
       password: "MyPassword",
       secret_key: "123123",
diff --git a/lib/shippex/carrier.ex b/lib/shippex/carrier.ex
index a023d15..f7a3bf4 100644
--- a/lib/shippex/carrier.ex
+++ b/lib/shippex/carrier.ex
@@ -4,7 +4,7 @@ defmodule Shippex.Carrier do
   function for fetching the Carrier module.
   """
 
-  alias Shippex.{Shipment, Service, Rate, Transaction}
+  alias Shippex.{Shipment, Service, Rate, Transaction, Util}
 
   @callback fetch_rates(Shipment.t()) :: [{atom, Rate.t()}]
   @callback fetch_rate(Shipment.t(), Service.t()) :: [{atom, Rate.t()}] | {atom, Rate.t()}
@@ -15,6 +15,7 @@ defmodule Shippex.Carrier do
   @callback validate_address(Address.t()) :: {:ok, [Address.t()]} | {:error, any()}
   @callback track_packages(String.t() | [String.t()]) :: {:ok | :error, any()}
   @callback services_country?(ISO.country_code()) :: boolean()
+  @callback carrier() :: atom
 
   @type t() :: atom()
 
@@ -31,13 +32,22 @@ defmodule Shippex.Carrier do
   @spec module(atom | String.t()) :: module()
   def module(carrier) when is_atom(carrier) do
     # NOTE, this might be a good place to use a protocol?
+    default_modules = Util.get_modules()
 
     carriers =
       Application.get_env(:shippex, :carriers, [])
-      |> Enum.with_index(fn(c, i) ->
-        module = List.first(c).module
-        {i, module}
+      |> Enum.with_index(fn c, i ->
+        module = Keyword.get(c, :module)
+
+        case module do
+          nil ->
+            Enum.filter(default_modules, fn {_module, module_carrier} -> module_carrier == i end)
+
+          module ->
+            {i, module}
+        end
       end)
+      |> Enum.reject(fn x -> x == nil end)
 
     module =
       case Enum.filter(carriers, fn {x, _} -> x == carrier end) do
diff --git a/lib/shippex/carrier/dummy.ex b/lib/shippex/carrier/dummy.ex
index 1a14779..c5339a7 100644
--- a/lib/shippex/carrier/dummy.ex
+++ b/lib/shippex/carrier/dummy.ex
@@ -47,10 +47,11 @@ defmodule Shippex.Carrier.Dummy do
   end
 
   defp rate() do
+    {carrier, _} = carrier()
     %Shippex.Rate{
       service: %Shippex.Service{
         id: :dummy,
-        carrier: carrier(),
+        carrier: carrier,
         description: "Dummy Shipping Service"
       },
       price: 1000,
@@ -61,7 +62,9 @@ defmodule Shippex.Carrier.Dummy do
   defp shipment() do
   end
 
-  defp carrier() do
+  @impl true
+  def carrier() do
     :dummy
   end
+
 end
diff --git a/lib/shippex/carrier/ups.ex b/lib/shippex/carrier/ups.ex
index dc51069..30fcd88 100644
--- a/lib/shippex/carrier/ups.ex
+++ b/lib/shippex/carrier/ups.ex
@@ -445,4 +445,9 @@ defmodule Shippex.Carrier.UPS do
         raise InvalidConfigError, message: "USPS config is either invalid or not found."
     end
   end
+
+  @impl true
+  def carrier() do
+    :ups
+  end
 end
diff --git a/lib/shippex/carrier/usps.ex b/lib/shippex/carrier/usps.ex
index 971c8f3..7f2a151 100644
--- a/lib/shippex/carrier/usps.ex
+++ b/lib/shippex/carrier/usps.ex
@@ -519,4 +519,9 @@ defmodule Shippex.Carrier.USPS do
         raise InvalidConfigError, message: "UPS config is either invalid or not found."
     end
   end
+
+  @impl true
+  def carrier() do
+    :usps
+  end
 end
diff --git a/lib/shippex/util.ex b/lib/shippex/util.ex
index 2e27872..6d57af3 100644
--- a/lib/shippex/util.ex
+++ b/lib/shippex/util.ex
@@ -180,4 +180,30 @@ defmodule Shippex.Util do
       {key, val}
     end
   end
+
+  @doc """
+  Returns the mane and module tuple.
+
+      iex> Util.get_modules()
+      {%{}, :module_name}
+  """
+  def get_modules() do
+    {:ok, modules} = :application.get_key(:shippex, :modules)
+
+    modules
+    |> Stream.map(&Module.split/1)
+    |> Stream.filter(fn module ->
+      case module do
+        ["Shippex", "Carrier", _] -> true
+        ["Shippex", "Carrier", "_", "Client"] -> false
+        _ -> false
+      end
+    end)
+    # concat
+    |> Stream.map(&Module.concat/1)
+    |> Stream.map(&{&1, apply(&1, :carrier, [])})
+    |> Enum.map(fn output ->
+      output
+    end)
+  end
 end