diff --git a/index.js b/index.js
index 47cd049..3657a7e 100644
--- a/index.js
+++ b/index.js
@@ -1,11 +1,79 @@
 var http = require ('httpreq');
+
+// Defaults
 var config = {
   email: null,
   apikey: null,
   timeout: 5000
 };
 
-function talk (props, callback) {
+
+/**
+ * Process API response
+ *
+ * @callback callback
+ * @param options {object} - httpreq options
+ * @param err {Error|null} - httpreq Error
+ * @param res {object} - httpreq response
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function apiResponse (options, err, res, callback) {
+  var type = res && res.headers ['content-type'] .split (';') [0] || '';
+  var size = res && res.headers ['content-length'] || null;
+  var code = res && res.statusCode;
+  var data = res && res.body || null;
+  var error = null;
+
+  if (err) {
+    error = new Error ('request failed');
+    error.error = err;
+    callback (error);
+    return;
+  }
+
+  if (size && options.binary && type.match (/\/(pdf|jpeg|tar)$/)) {
+    callback (null, data);
+    return;
+  }
+
+  try {
+    data = JSON.parse (data);
+  } catch (e) {
+    error = new Error ('invalid response');
+    error.statusCode = code;
+    error.contentType = type;
+    error.error = e;
+    data = null;
+  }
+
+  if (data && data.error) {
+    error = new Error ('API error');
+    error.statusCode = code;
+    error.contentType = type;
+    error.error = data.error;
+    data = null;
+  }
+
+  callback (error, data);
+}
+
+
+/**
+ * Send API request
+ *
+ * @callback callback
+ * @param props {object}
+ * @param [props.binary=false] {boolean} - Expect binary response
+ * @param [props.method=GET] {string} - HTTP method
+ * @param [props.params] {object} - Method parameters
+ * @param props.path {string} - Method path
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function apiRequest (props, callback) {
   var options = {
     url: 'https://gtmetrix.com/api/0.1/' + props.path,
     parameters: props.params || null,
@@ -19,46 +87,140 @@ function talk (props, callback) {
   };
 
   http.doRequest (options, function (err, res) {
-    var type = res && res.headers ['content-type'] .split (';') [0] || '';
-    var size = res && res.headers ['content-length'] || null;
-    var code = res && res.statusCode;
-    var data = res && res.body || null;
-    var error = null;
-
-    if (err) {
-      error = new Error ('request failed');
-      error.error = err;
-      callback (error);
-      return;
-    }
+    apiResponse (options, err, res, callback);
+  });
+}
 
-    if (size && props.binary && type.match (/\/(pdf|jpeg|tar)$/)) {
-      callback (null, data);
-      return;
-    }
 
-    try {
-      data = JSON.parse (data);
-    } catch (e) {
-      error = new Error ('invalid response');
-      error.statusCode = code;
-      error.contentType = type;
-      error.error = e;
-      data = null;
-    }
+/**
+ * Create test
+ *
+ * @callback callback
+ * @param params {object}
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
 
-    if (data && data.error) {
-      error = new Error ('API error');
-      error.statusCode = code;
-      error.contentType = type;
-      error.error = data.error;
-      data = null;
-    }
+function testCreate (params, callback) {
+  var props = {
+    method: 'POST',
+    path: 'test',
+    params: params
+  };
 
-    callback (error, data);
-  });
+  apiRequest (props, callback);
 }
 
+
+/**
+ * Get test result
+ *
+ * @callback callback
+ * @param testId {object}
+ * @param [resouce] {string} - Resource to get, i.e. `screenshot`
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function testGet (testId, resource, callback) {
+  var props = {
+    method: 'GET',
+    path: 'test/' + testId
+  };
+
+  if (typeof resource === 'string') {
+    props.path += '/' + resource;
+    props.binary = resource.match (/(screenshot)/);
+  } else {
+    callback = resource;
+  }
+
+  apiRequest (props, callback);
+}
+
+/**
+ * List locations
+ *
+ * @callback callback
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function locationsList (callback) {
+  var props = {
+    method: 'GET',
+    path: 'locations'
+  };
+
+  apiRequest (props, callback);
+}
+
+
+/**
+ * List browsers
+ *
+ * @callback callback
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function browsersList (callback) {
+  var props = {
+    method: 'GET',
+    path: 'browsers'
+  };
+
+  apiRequest (props, callback);
+}
+
+
+/**
+ * Get browser
+ *
+ * @callback callback
+ * @param browserId {string}
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function browsersGet (browserId, callback) {
+  var props = {
+    method: 'GET',
+    path: 'browsers/' + browserId
+  };
+
+  apiRequest (props, callback);
+}
+
+
+/**
+ * Get account status
+ *
+ * @callback callback
+ * @param callback {function} - `(err, data)`
+ * @return {void}
+ */
+
+function accountStatus (callback) {
+  var props = {
+    method: 'GET',
+    path: 'status'
+  };
+
+  apiRequest (props, callback);
+}
+
+
+/**
+ * Module interface
+ *
+ * @param props {object}
+ * @param props.email {string} - API email
+ * @param props.apikey {string} - API key
+ * @param [props.timeout=5000] {number} - Request timeut in ms
+ * @return {object} - Methods
+ */
+
 module.exports = function (props) {
   var key;
 
@@ -68,42 +230,18 @@ module.exports = function (props) {
 
   return {
     test: {
-      create: function (params, callback) {
-        talk ({ method: 'POST', path: 'test', params: params }, callback);
-      },
-      get: function (testId, resource, callback) {
-        var params = {
-          method: 'GET',
-          path: 'test/' + testId
-        };
-
-        if (typeof resource === 'string') {
-          params.path += '/' + resource;
-          params.binary = resource.match (/(screenshot)/);
-        } else {
-          callback = resource;
-        }
-
-        talk (params, callback);
-      }
+      create: testCreate,
+      get: testGet
     },
     locations: {
-      list: function (callback) {
-        talk ({ method: 'GET', path: 'locations' }, callback);
-      }
+      list: locationsList
     },
     browsers: {
-      list: function (callback) {
-        talk ({ method: 'GET', path: 'browsers' }, callback);
-      },
-      get: function (browserId, callback) {
-        talk ({ method: 'GET', path: 'browsers/' + browserId }, callback);
-      }
+      list: browsersList,
+      get: browsersGet
     },
     account: {
-      status: function (callback) {
-        talk ({ method: 'GET', path: 'status' }, callback);
-      }
+      status: accountStatus
     }
   };
 };