diff --git a/README.md b/README.md
index ea9397b..ab81eaa 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,23 @@ An Elixir client for the Amplitude HTTP API
 
   ```elixir
   def deps do
-    [{:amplitude, "~> 0.2.0"}]
+    [{:amplitude, "~> 0.3.0"}]
   end
   ```
 
+  2. Set your `api_key` in `config.exs`, for example from an enviroment variable:
+  ```elixir
+  config :amplitude,
+    api_key: System.get_env("MY_AMPLITUDE_KEY")
+  ```
+
+## Testing
+  Add this to `test.exs` so it doesn't make api requests in test enviroment:
+  ```elixir
+    config :amplitude,
+      track_api_url: "test",
+      identify_api_url: "test"
+  ```
 ## Usage
 
   1. Track events with the `Amplitude.track/4` function:
diff --git a/lib/amplitude.ex b/lib/amplitude.ex
index 4f73271..7beda13 100644
--- a/lib/amplitude.ex
+++ b/lib/amplitude.ex
@@ -21,7 +21,7 @@ defmodule Amplitude do
       "success"
   """
   @spec track(String.t(), String.t(), map(), map(), keyword()) ::
-          {:ok, "success"} | {:error, String.t()}
+          {:ok, String.t()} | {:error, String.t()}
   def track(event_type, user_id, event_props \\ %{}, user_props \\ %{}, opts \\ [])
 
   def track(event_type, user_id, event_props, user_props, opts) do
@@ -41,7 +41,7 @@ defmodule Amplitude do
       ...> response
       "success"
   """
-  @spec track(String.t(), map(), map(), keyword()) :: {:ok, "success"} | {:error, String.t()}
+  @spec identify(String.t(), map(), map(), keyword()) :: {:ok, String.t()} | {:error, String.t()}
   def identify(user_id, user_props, identify_props \\ %{}, opts \\ [])
 
   def identify(user_id, user_props, identify_props, opts) do
diff --git a/lib/api/fake.ex b/lib/api/fake.ex
index e6b177a..21c3735 100644
--- a/lib/api/fake.ex
+++ b/lib/api/fake.ex
@@ -12,6 +12,6 @@ defmodule Amplitude.API.Fake do
          do: Poison.decode(content)
   end
 
-  def api_track(_), do: load("/track/response.txt")
-  def api_identify(_), do: load("/identify/response.txt")
+  def api_track(_, _), do: load("/track/response.txt")
+  def api_identify(_, _), do: load("/identify/response.txt")
 end
diff --git a/mix.exs b/mix.exs
index ffa55b8..ce9e8f4 100644
--- a/mix.exs
+++ b/mix.exs
@@ -18,7 +18,7 @@ defmodule Amplitude.Mixfile do
   #
   # Type "mix help compile.app" for more information
   def application do
-    [applications: [:logger]]
+    [applications: [:logger, :poison]]
   end
 
   # Dependencies can be Hex packages:
diff --git a/mix.lock b/mix.lock
index 35a92f0..af3fe97 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,18 +1,18 @@
 %{
-  "certifi": {:hex, :certifi, "2.4.2", "75424ff0f3baaccfd34b1214184b6ef616d89e420b258bb0a5ea7d7bc628f7f0", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
-  "earmark": {:hex, :earmark, "1.3.1", "73812f447f7a42358d3ba79283cfa3075a7580a3a2ed457616d6517ac3738cb9", [:mix], [], "hexpm"},
-  "elixir_uuid": {:hex, :elixir_uuid, "1.2.0", "ff26e938f95830b1db152cb6e594d711c10c02c6391236900ddd070a6b01271d", [:mix], [], "hexpm"},
-  "ex_doc": {:hex, :ex_doc, "0.19.3", "3c7b0f02851f5fc13b040e8e925051452e41248f685e40250d7e40b07b9f8c10", [:mix], [{:earmark, "~> 1.2", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.10", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
-  "hackney": {:hex, :hackney, "1.14.3", "b5f6f5dcc4f1fba340762738759209e21914516df6be440d85772542d4a5e412", [:rebar3], [{:certifi, "2.4.2", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.4", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
-  "httpoison": {:hex, :httpoison, "1.5.0", "71ae9f304bdf7f00e9cd1823f275c955bdfc68282bc5eb5c85c3a9ade865d68e", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
-  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup": {:hex, :makeup, "0.8.0", "9cf32aea71c7fe0a4b2e9246c2c4978f9070257e5c9ce6d4a28ec450a839b55f", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.13.0", "be7a477997dcac2e48a9d695ec730b2d22418292675c75aa2d34ba0909dcdeda", [:mix], [{:makeup, "~> 0.8", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
-  "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
-  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm"},
-  "nimble_parsec": {:hex, :nimble_parsec, "0.5.0", "90e2eca3d0266e5c53f8fbe0079694740b9c91b6747f2b7e3c5d21966bba8300", [:mix], [], "hexpm"},
-  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm"},
-  "poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [:mix], [], "hexpm"},
-  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm"},
-  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm"},
+  "certifi": {:hex, :certifi, "2.4.2", "75424ff0f3baaccfd34b1214184b6ef616d89e420b258bb0a5ea7d7bc628f7f0", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm", "01d479edba0569a7b7a2c8bf923feeb6dc6a358edc2965ef69aea9ba288bb243"},
+  "earmark": {:hex, :earmark, "1.3.1", "73812f447f7a42358d3ba79283cfa3075a7580a3a2ed457616d6517ac3738cb9", [:mix], [], "hexpm", "000aaeff08919e95e7aea13e4af7b2b9734577b3e6a7c50ee31ee88cab6ec4fb"},
+  "elixir_uuid": {:hex, :elixir_uuid, "1.2.0", "ff26e938f95830b1db152cb6e594d711c10c02c6391236900ddd070a6b01271d", [:mix], [], "hexpm", "e4d6e26434471761ed45a3545239da87af7b70904dd4442a55f87d06b137c56b"},
+  "ex_doc": {:hex, :ex_doc, "0.19.3", "3c7b0f02851f5fc13b040e8e925051452e41248f685e40250d7e40b07b9f8c10", [:mix], [{:earmark, "~> 1.2", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.10", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm", "0e11d67e662142fc3945b0ee410c73c8c956717fbeae4ad954b418747c734973"},
+  "hackney": {:hex, :hackney, "1.14.3", "b5f6f5dcc4f1fba340762738759209e21914516df6be440d85772542d4a5e412", [:rebar3], [{:certifi, "2.4.2", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.4", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm", "ed15491f324aa0e95647dca8ef4340418dac479d1204d57e455d52dcfba3f705"},
+  "httpoison": {:hex, :httpoison, "1.5.0", "71ae9f304bdf7f00e9cd1823f275c955bdfc68282bc5eb5c85c3a9ade865d68e", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "e9d994aea63fab9e29307920492ab95f87339b56fbc5c8c4b1f65ea20d3ba9a4"},
+  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "4bdd305eb64e18b0273864920695cb18d7a2021f31a11b9c5fbcd9a253f936e2"},
+  "makeup": {:hex, :makeup, "0.8.0", "9cf32aea71c7fe0a4b2e9246c2c4978f9070257e5c9ce6d4a28ec450a839b55f", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "5fbc8e549aa9afeea2847c0769e3970537ed302f93a23ac612602e805d9d1e7f"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.13.0", "be7a477997dcac2e48a9d695ec730b2d22418292675c75aa2d34ba0909dcdeda", [:mix], [{:makeup, "~> 0.8", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "adf0218695e22caeda2820eaba703fa46c91820d53813a2223413da3ef4ba515"},
+  "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
+  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm", "7a4c8e1115a2732a67d7624e28cf6c9f30c66711a9e92928e745c255887ba465"},
+  "nimble_parsec": {:hex, :nimble_parsec, "0.5.0", "90e2eca3d0266e5c53f8fbe0079694740b9c91b6747f2b7e3c5d21966bba8300", [:mix], [], "hexpm", "5c040b8469c1ff1b10093d3186e2e10dbe483cd73d79ec017993fb3985b8a9b3"},
+  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm", "17ef63abde837ad30680ea7f857dd9e7ced9476cdd7b0394432af4bfc241b960"},
+  "poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [:mix], [], "hexpm", "fec8660eb7733ee4117b85f55799fd3833eb769a6df71ccf8903e8dc5447cfce"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm", "603561dc0fd62f4f2ea9b890f4e20e1a0d388746d6e20557cafb1b16950de88c"},
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm", "1d1848c40487cdb0b30e8ed975e34e025860c02e419cb615d255849f3427439d"},
 }