diff --git a/.doclets.yml b/.doclets.yml
new file mode 100644
index 0000000..ad6b950
--- /dev/null
+++ b/.doclets.yml
@@ -0,0 +1,10 @@
+dir: .
+packageJson: package.json
+articles:
+  - Overview: README.md
+  - API Provider: apis/README.md
+  - Changelog: CHANGELOG.md
+  - License: LICENSE
+branches:
+  - master
+  - develop
diff --git a/.eslintignore b/.eslintignore
new file mode 100644
index 0000000..a188e06
--- /dev/null
+++ b/.eslintignore
@@ -0,0 +1 @@
+docs/*
diff --git a/.eslintrc b/.eslintrc
index db007e4..f8aff93 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -4,7 +4,8 @@
     "comma-dangle": 0,
 	"indent": [2, 4],
     "max-len": [2, 120, { "ignoreStrings": true }],
-    "radix": [2, "as-needed"]
+    "radix": [2, "as-needed"],
+    "no-console": 0
   },
   "settings": {
     "import/core-modules": [ "node_helper" ]
@@ -14,4 +15,4 @@
     "node": true,
     "es6": true
   }
-}
\ No newline at end of file
+}
diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
new file mode 100644
index 0000000..5956f32
--- /dev/null
+++ b/.github/CONTRIBUTING.md
@@ -0,0 +1,8 @@
+# Contribution Guidelines
+
+Thanks for contributing to this module!
+
+Please create pull requests to the branch `develop`.
+
+To hold one code style and standard there are several linters and tools in this project set. Make sure you fullfill the requirements.
+Also there will be automatically analysis performed once you created the pull request.
diff --git a/.github/ISSUE_TEMPLATE.md b/.github/ISSUE_TEMPLATE.md
new file mode 100644
index 0000000..5bbae68
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE.md
@@ -0,0 +1,9 @@
+Platform (Hardware/OS):
+
+Node version:
+
+MagicMirror version:
+
+Module version:
+
+Description of the issue:
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..63fa699
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,5 @@
+Please create pull requests to the branch `develop`.
+
+* Does the pull request solve an issue (add a reference)?
+* What are the features of this pr?
+* Add screenshots for visual changes.
diff --git a/.mdlrc b/.mdlrc
index e0ea98e..54d0111 100644
--- a/.mdlrc
+++ b/.mdlrc
@@ -1,2 +1,2 @@
 all
-rules "~MD013", "~MD033"
\ No newline at end of file
+rules "~MD013", "~MD026", "~MD033"
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..99aa6b9
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,23 @@
+# MMM-WienerLinien Changelog
+
+## [1.1.0]
+
+### Added
+
+* API provider development [Guide](apis).
+* API provider `spritpreisrechner.at`.
+* Disabled markdownlint rule `MD026` (no-trailing-punctuation)
+* Disabled eslint rule `no-console`
+* Documentation
+* [Doclets.io](https://doclets.io/fewieden/MMM-Fuel/master) integration
+* Contributing guidelines
+* Issue template
+* Pull request template
+
+### Changed
+
+* Outsourced API provider `tankerkoenig.de`.
+
+## [1.0.0]
+
+Initial version
diff --git a/MMM-Fuel.js b/MMM-Fuel.js
index a99d595..eb27d92 100644
--- a/MMM-Fuel.js
+++ b/MMM-Fuel.js
@@ -1,20 +1,74 @@
-/* global Module Log google*/
-
-/* Magic Mirror
- * Module: MMM-Fuel
+/**
+ * @file MMM-Fuel.js
+ *
+ * @author fewieden
+ * @license MIT
  *
- * By fewieden https://github.com/fewieden/MMM-Fuel
- * MIT Licensed.
+ * @see  https://github.com/fewieden/MMM-Fuel
+ */
+
+/* global Module Log config google */
+
+/**
+ * @external Module
+ * @see https://github.com/MichMich/MagicMirror/blob/master/js/module.js
+ */
+
+/**
+ * @external Log
+ * @see https://github.com/MichMich/MagicMirror/blob/master/js/logger.js
  */
 
+/**
+ * @module MMM-Fuel
+ * @description Frontend for the module to display data.
+ *
+ * @requires external:Module
+ * @requires external:Log
+ */
 Module.register('MMM-Fuel', {
 
+    /** @member {Object} units - Is used to determine the unit symbol of the global config option units. */
+    units: {
+        imperial: 'ml',
+        metric: 'km'
+    },
+
+    /** @member {Object} currencies - Is used to convert currencies into symbols. */
+    currencies: {
+        EUR: '€'
+    },
+
+    /** @member {boolean} sortByPrice - Flag to switch between sorting (price and distance). */
     sortByPrice: true,
+    /** @member {boolean} help - Flag to switch between render help or not. */
     help: false,
+    /** @member {boolean} map - Flag to switch between render map or not. */
     map: false,
-    mapUI: null,
+    /** @member {?Interval} interval - Toggles sortByPrice */
     interval: null,
 
+    /**
+     * @member {Object} defaults - Defines the default config values.
+     * @property {int} radius - Lookup area for gas stations.
+     * @property {int} max - Amount of gas stations to display.
+     * @property {boolean|string} map_api_key - API key for Google Maps.
+     * @property {int} zoom - Zoom level of the map.
+     * @property {int} width - Width of the map.
+     * @property {int} height - Height of the map.
+     * @property {boolean} colored - Flag to render map in colour or greyscale.
+     * @property {boolean} open - Flag to render column to indicate if the gas stations are open or closed.
+     * @property {boolean|int} shortenText - Max characters to be shown for name and address.
+     * @property {boolean} showAddress - Flag to show the gas stations address.
+     * @property {boolean} showOpenOnly - Flag to show only open gas stations or all.
+     * @property {boolean} iconHeader - Flag to display the car icon in the header.
+     * @property {boolean} rotate - Flag to enable/disable rotation between sort by price and distance.
+     * @property {string[]} types - Fuel types to show.
+     * @property {string} sortBy - Type to sort by price.
+     * @property {int} rotateInterval - Speed of rotation.
+     * @property {int} updateInterval - Speed of update.
+     * @property {string} provider - API provider of the data.
+     */
     defaults: {
         radius: 5,
         max: 5,
@@ -31,10 +85,16 @@ Module.register('MMM-Fuel', {
         rotate: true,
         types: ['diesel'],
         sortBy: 'diesel',
-        rotateInterval: 60 * 1000,           // every minute
-        updateInterval: 15 * 60 * 1000       // every 15 minutes
+        rotateInterval: 60 * 1000, // every minute
+        updateInterval: 15 * 60 * 1000, // every 15 minutes
+        provider: 'tankerkoenig'
     },
 
+    /**
+     * @member {Object} voice - Defines the voice recognition part.
+     * @property {string} mode - MMM-voice mode of this module.
+     * @property {string[]} sentences - All commands of this module.
+     */
     voice: {
         mode: 'FUEL',
         sentences: [
@@ -45,6 +105,12 @@ Module.register('MMM-Fuel', {
         ]
     },
 
+    /**
+     * @function getTranslations
+     * @description Translations for this module.
+     *
+     * @returns {Object.<string, string>} Available translations for this module (key: language code, value: filepath).
+     */
     getTranslations() {
         return {
             en: 'translations/en.json',
@@ -52,10 +118,22 @@ Module.register('MMM-Fuel', {
         };
     },
 
+    /**
+     * @function getStyles
+     * @description Style dependencies for this module.
+     *
+     * @returns {string[]} List of the style dependency filepaths.
+     */
     getStyles() {
         return ['font-awesome.css', 'MMM-Fuel.css'];
     },
 
+    /**
+     * @function start
+     * @description Appends Google Map script to the body, if the config option map_api_key is defined. Calls
+     * createInterval and sends the config to the node_helper.
+     * @override
+     */
     start() {
         Log.info(`Starting module: ${this.name}`);
         // Add script manually, getScripts doesn't work for it!
@@ -68,6 +146,11 @@ Module.register('MMM-Fuel', {
         this.sendSocketNotification('CONFIG', this.config);
     },
 
+    /**
+     * @function createInterval
+     * @description Creates an interval if config option rotate is set.
+     * @returns {?Interval} The Interval toggles sortByPrice between true and false.
+     */
     createInterval() {
         if (!this.config.rotate) {
             return null;
@@ -78,6 +161,14 @@ Module.register('MMM-Fuel', {
         }, this.config.rotateInterval);
     },
 
+    /**
+     * @function notificationReceived
+     * @description Handles incoming broadcasts from other modules or the MagicMirror core.
+     *
+     * @param {string} notification - Notification name
+     * @param {*} payload - Detailed payload of the notification.
+     * @param {MM} [sender] - The sender of the notification. If sender is undefined the sender is the core.
+     */
     notificationReceived(notification, payload, sender) {
         if (notification === 'ALL_MODULES_STARTED') {
             this.sendNotification('REGISTER_VOICE_MODULE', this.voice);
@@ -90,6 +181,13 @@ Module.register('MMM-Fuel', {
         }
     },
 
+    /**
+     * @function socketNotificationReceived
+     * @description Handles incoming messages from node_helper.
+     *
+     * @param {string} notification - Notification name
+     * @param {*} payload - Detailed payload of the notification.
+     */
     socketNotificationReceived(notification, payload) {
         if (notification === 'PRICELIST') {
             this.priceList = payload;
@@ -97,6 +195,13 @@ Module.register('MMM-Fuel', {
         }
     },
 
+    /**
+     * @function getDom
+     * @description Creates the UI as DOM for displaying in MagicMirror application.
+     * @override
+     *
+     * @returns {Element}
+     */
     getDom() {
         const wrapper = document.createElement('div');
         const list = document.createElement('div');
@@ -159,8 +264,8 @@ Module.register('MMM-Fuel', {
                         const script = document.createElement('script');
                         script.innerHTML = `var MMM_Fuel_map = \
                             new google.maps.Map(document.querySelector('div.MMM-Fuel-map'), \
-                            {center: new google.maps.LatLng(${parseFloat(this.config.lat)}, \
-                            ${parseFloat(this.config.lng)}), zoom: ${this.config.zoom}, disableDefaultUI:true});
+                            {center: new google.maps.LatLng(${this.config.lat}, \
+                            ${this.config.lng}), zoom: ${this.config.zoom}, disableDefaultUI:true});
                             var trafficLayer = new google.maps.TrafficLayer();
                             trafficLayer.setMap(MMM_Fuel_map);
                             var MMM_Fuel_array = ${JSON.stringify(this.priceList.byPrice)};
@@ -186,6 +291,12 @@ Module.register('MMM-Fuel', {
         return wrapper;
     },
 
+    /**
+     * @function createLabelRow
+     * @description Creates label row for price table.
+     *
+     * @returns {Element}
+     */
     createLabelRow() {
         const labelRow = document.createElement('tr');
 
@@ -198,20 +309,20 @@ Module.register('MMM-Fuel', {
         labelRow.appendChild(sortLabel);
 
         for (let i = 0; i < this.config.types.length; i += 1) {
-            const typeLabel = document.createElement('th');
-            typeLabel.classList.add('centered');
+            if (this.priceList.types.includes(this.config.types[i])) {
+                const typeLabel = document.createElement('th');
+                typeLabel.classList.add('centered');
 
-            const typeSpan = document.createElement('span');
-            typeSpan.innerHTML = this.config.types[i].charAt(0).toUpperCase() + this.config.types[i].slice(1);
-            typeLabel.appendChild(typeSpan);
+                const typeSpan = document.createElement('span');
+                typeSpan.innerHTML = this.capitalizeFirstLetter(this.config.types[i]);
+                typeLabel.appendChild(typeSpan);
 
-            if (this.sortByPrice && this.config.sortBy === this.config.types[i]) {
-                const sortIcon = document.createElement('i');
-                sortIcon.classList.add('fa', 'fa-long-arrow-down', 'sortBy');
-                typeLabel.appendChild(sortIcon);
-            }
+                if (this.sortByPrice && this.config.sortBy === this.config.types[i]) {
+                    typeLabel.appendChild(this.createSortIcon());
+                }
 
-            labelRow.appendChild(typeLabel);
+                labelRow.appendChild(typeLabel);
+            }
         }
 
         const distanceIconLabel = document.createElement('th');
@@ -222,9 +333,7 @@ Module.register('MMM-Fuel', {
         distanceIconLabel.appendChild(distanceIcon);
 
         if (!this.sortByPrice) {
-            const sortIcon = document.createElement('i');
-            sortIcon.classList.add('fa', 'fa-long-arrow-down', 'sortBy');
-            distanceIconLabel.appendChild(sortIcon);
+            distanceIconLabel.appendChild(this.createSortIcon());
         }
 
         labelRow.appendChild(distanceIconLabel);
@@ -241,6 +350,14 @@ Module.register('MMM-Fuel', {
         return labelRow;
     },
 
+    /**
+     * @function shortenText
+     * @description Shortens text based on config option (shortenText) and adds ellipsis at the end.
+     *
+     * @param {string} text - Text which should be shorten.
+     *
+     * @returns {string} The shortened text.
+     */
     shortenText(text) {
         let temp = text;
         if (this.config.shortenText && temp.length > this.config.shortenText) {
@@ -249,6 +366,33 @@ Module.register('MMM-Fuel', {
         return temp;
     },
 
+    /**
+     * @function appendDataRow
+     * @description Creates the UI for the station price table.
+     *
+     * @param {Object} data - Information about a station.
+     * @param {string} data.name - The gas station name.
+     * @param {Object.<string, number>} data.prices - Prices (value) of the different fuel types (key).
+     * @param {number} data.distance - Distance between user location and gas station.
+     * @param {boolean} data.isOpen - Indicator if the gas station is currently open or closed.
+     * @param {string} data.address - Address of the gas station in the format: Postcode City - Street Housenumber.
+     * @param {Element} appendTo - DOM Element where the UI gets appended as child.
+     *
+     * @example <caption>data object</caption>
+     * {
+     *   "name": "Aral Tankstelle",
+     *   "prices": {
+     *     "diesel": 1.009,
+     *     "e5": 1.009,
+     *     "e10": 1.009
+     *   },
+     *   "distance": 2.2,
+     *   "isOpen": true,
+     *   "address": "70372 Stuttgart - Waiblinger Straße 23-25",
+     *   "lat": 48.8043442,
+     *   "lng": 9.220273
+     * }
+     */
     appendDataRow(data, appendTo) {
         const row = document.createElement('tr');
 
@@ -257,16 +401,30 @@ Module.register('MMM-Fuel', {
         row.appendChild(name);
 
         for (let i = 0; i < this.config.types.length; i += 1) {
-            const price = document.createElement('td');
-            price.classList.add('centered');
-            price.innerHTML = `${data[this.config.types[i]]} €`;
-            row.appendChild(price);
+            if (this.priceList.types.includes(this.config.types[i])) {
+                const price = document.createElement('td');
+                price.classList.add('centered');
+                if (data.prices[this.config.types[i]] === -1) {
+                    price.innerHTML = '-';
+                } else {
+                    price.innerHTML = `${data.prices[this.config.types[i]].toFixed(2)} ${
+                        this.currencies[this.priceList.currency]}`;
+                }
+                row.appendChild(price);
+            }
         }
 
-        const distance = document.createElement('td');
-        distance.classList.add('centered');
-        distance.innerHTML = `${data.dist} km`;
-        row.appendChild(distance);
+        const distanceUnit = this.units[config.units];
+        let distance = data.distance;
+
+        if (distanceUnit !== this.priceList.unit) {
+            distance = this[`${this.priceList.unit}2${distanceUnit}`](distance);
+        }
+
+        const distanceColumn = document.createElement('td');
+        distanceColumn.classList.add('centered');
+        distanceColumn.innerHTML = `${distance.toFixed(2)} ${distanceUnit}`;
+        row.appendChild(distanceColumn);
 
         if (this.config.open) {
             const lockUnlockIconLabel = document.createElement('td');
@@ -289,14 +447,19 @@ Module.register('MMM-Fuel', {
 
             const address = document.createElement('td');
             address.classList.add('xsmall');
-            address.innerHTML = this.shortenText(`${(`0${data.postCode}`).slice(-5)} ${data.place} - ${data.street
-                } ${data.houseNumber}`);
+            address.innerHTML = this.shortenText(data.address);
             details.appendChild(address);
 
             appendTo.appendChild(details);
         }
     },
 
+    /**
+     * @function checkCommands
+     * @description Checks for voice commands.
+     *
+     * @param {string} data - Text with commands.
+     */
     checkCommands(data) {
         if (/(HELP)/g.test(data)) {
             if (/(CLOSE)/g.test(data) || (this.help && !/(OPEN)/g.test(data))) {
@@ -318,6 +481,12 @@ Module.register('MMM-Fuel', {
         this.updateDom(300);
     },
 
+    /**
+     * @function appendTo
+     * @description Creates the UI for the voice command SHOW HELP.
+     *
+     * @param {Element} appendTo - DOM Element where the UI gets appended as child.
+     */
     appendHelp(appendTo) {
         const title = document.createElement('h1');
         title.classList.add('medium');
@@ -339,5 +508,54 @@ Module.register('MMM-Fuel', {
             list.appendChild(item);
         }
         appendTo.appendChild(list);
+    },
+
+    /**
+     * @function createSortIcon
+     * @description Creates a DOM Element with the FontAwesome icon
+     * fa-long-arrow-down {@link http://fontawesome.io/icons/}.
+     *
+     * @returns {Element} Element with icon.
+     */
+    createSortIcon() {
+        const sortIcon = document.createElement('i');
+        sortIcon.classList.add('fa', 'fa-long-arrow-down', 'sortBy');
+        return sortIcon;
+    },
+
+    /**
+     * @function capitalizeFirstLetter
+     * @description Capitalizes the first character in a string.
+     *
+     * @param {string} text - text to capitalize the first letter.
+     *
+     * @returns {string} Capitalized string.
+     */
+    capitalizeFirstLetter(text) {
+        return text.charAt(0).toUpperCase() + text.slice(1);
+    },
+
+    /**
+     * @function km2ml
+     * @description Converts the unit kilometres to miles.
+     *
+     * @param {number} value - Distance in kilometres.
+     *
+     * @returns {number} Distance in miles.
+     */
+    km2ml(value) {
+        return value * 0.62137;
+    },
+
+    /**
+     * @function ml2km
+     * @description Converts the unit miles to kilometres.
+     *
+     * @param {number} value - Distance in miles.
+     *
+     * @returns {number} Distance in kilometres.
+     */
+    ml2km(value) {
+        return value * 1.60934;
     }
 });
diff --git a/README.md b/README.md
index a4c0a58..535a486 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,10 @@
-# MMM-Fuel [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg?style=flat)](https://raw.githubusercontent.com/fewieden/MMM-Fuel/master/LICENSE) [![Build Status](https://travis-ci.org/fewieden/MMM-Fuel.svg?branch=master)](https://travis-ci.org/fewieden/MMM-Fuel) [![Code Climate](https://codeclimate.com/github/fewieden/MMM-Fuel/badges/gpa.svg?style=flat)](https://codeclimate.com/github/fewieden/MMM-Fuel) [![Known Vulnerabilities](https://snyk.io/test/github/fewieden/mmm-fuel/badge.svg)](https://snyk.io/test/github/fewieden/mmm-fuel)
+[![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg?style=flat)](https://raw.githubusercontent.com/fewieden/MMM-Fuel/master/LICENSE) [![Build Status](https://travis-ci.org/fewieden/MMM-Fuel.svg?branch=master)](https://travis-ci.org/fewieden/MMM-Fuel) [![Code Climate](https://codeclimate.com/github/fewieden/MMM-Fuel/badges/gpa.svg?style=flat)](https://codeclimate.com/github/fewieden/MMM-Fuel) [![Known Vulnerabilities](https://snyk.io/test/github/fewieden/mmm-fuel/badge.svg)](https://snyk.io/test/github/fewieden/mmm-fuel) [![API Doc](https://doclets.io/fewieden/MMM-Fuel/master.svg)](https://doclets.io/fewieden/MMM-Fuel/master)
 
-Gas Station price Module for MagicMirror<sup>2</sup>
+# MMM-Fuel
 
-## Example
+Gas Station Price Module for MagicMirror<sup>2</sup>
+
+## Examples
 
 ![](.github/example.jpg) ![](.github/example2.jpg) ![](.github/example3.jpg)
 
@@ -13,14 +15,6 @@ Gas Station price Module for MagicMirror<sup>2</sup>
 * npm
 * [request](https://www.npmjs.com/package/request)
 
-## Info
-
-The data used in this module comes from [tankerkoenig.de](http://www.tankerkoenig.de) and is only for Gas Stations in Germany.
-If you find an API for other countries let me know and i will implement them as well.
-
-Read the [Terms of Use](https://creativecommons.tankerkoenig.de/#usage) carefully, especially the restrictions for smart mirrors,
-or your API access will be suspended.
-
 ## Installation
 
 1. Clone this repo into `~/MagicMirror/modules` directory.
@@ -46,13 +40,13 @@ or your API access will be suspended.
 
 | **Option** | **Default** | **Description** |
 | --- | --- | --- |
-| `api_key` | REQUIRED | Get an API key for free access to the data of www.tankerkoenig.de [here](https://creativecommons.tankerkoenig.de/#register). |
+| `provider` | `"tankerkoenig"` | API provider (See full list below). |
 | `lat` | REQUIRED | Decimal degrees latitude. |
 | `lng` | REQUIRED | Decimal degrees longitude. |
-| `types` | `["diesel"]` | Fuel types in an array e.g. `["diesel", "e5"]` valid options: `"diesel"`, `"e5"` and `"e10"`. |
-| `sortBy` | `"diesel"` | Price sorting by which fuel type `"diesel"`, `"e5"` or `"e10"`. |
+| `types` | `["diesel"]` | Fuel types in an array e.g. `["diesel", "e5"]`. All valid types can be seen in the specific provider section below. |
+| `sortBy` | `"diesel"` | Price sorting by which fuel type defined in config option `types`. |
 | `open` | `false` | Display whether the gas station is open or not. |
-| `radius` | `5` | Lookup Area for Gas Stations in km. Possible values 1-25. |
+| `radius` | `5` | Lookup Area for Gas Stations in km. |
 | `max` | `5` | How many gas stations should be displayed. |
 | `map_api_key` | `false` | Required to show the gas stations map with traffic layer. You can get it [here](https://console.developers.google.com/) and don't forget to activate maps api for javascript. |
 | `zoom` | `12` | Zoom of the map. (Min 0, Max 18 depends on the area) |
@@ -67,6 +61,27 @@ or your API access will be suspended.
 | `rotateInterval` | `60000` (1 min) | How fast the sorting should be switched between byPrice and byDistance. |
 | `updateInterval` | `900000` (15 mins) | How often should the data be fetched. |
 
+### tankerkoenig (Germany only)
+
+Read the [Terms of Use](https://creativecommons.tankerkoenig.de/#usage) carefully, especially the restrictions for smart mirrors,
+or your API access will be suspended.
+
+| **Option** | **Default** | **Description** |
+| --- | --- | --- |
+| `api_key` | REQUIRED | Get an API key for free access to the data of [tankerkoenig.de](https://creativecommons.tankerkoenig.de/#register). |
+| `types` | `["diesel"]` | Valid options are `diesel`, `e5` and `e10`. |
+| `radius` | `5` | Valid range is 1-25. |
+
+### spritpreisrechner (Austria only)
+
+No API key required.
+
+| **Option** | **Default** | **Description** |
+| --- | --- | --- |
+| `types` | `["diesel"]` | Valid options are `diesel`, `e5` and `gas`. |
+| `radius` | `5` | Valid range not tested yet. |
+| `max` | `5` | The API provider returns maximum of 5 valid datasets. |
+
 ## OPTIONAL: Voice Control
 
 This module supports voice control by [MMM-voice](https://github.com/fewieden/MMM-voice). In order to use this feature, it's required to install the voice module. There are no extra config options for voice control needed.
@@ -81,3 +96,16 @@ The voice control mode for this module is `FUEL`
 * CLOSE HELP -> Hides the help information.
 * SHOW GAS STATIONS MAP -> Shows a map with the gas stations labeled by Price starting with 1.
 * HIDE GAS STATIONS MAP -> Hide the map.
+
+## Developer
+
+* `npm run lint` - Lints JS and CSS files.
+* `npm run docs` - Generates documentation.
+
+### Documentation
+
+The documentation can be found [here](https://doclets.io/fewieden/MMM-Fuel/master)
+
+### API Provider Development
+
+If you want to add another API provider checkout the [Guide](apis).
diff --git a/apis/README.md b/apis/README.md
new file mode 100644
index 0000000..55e4df2
--- /dev/null
+++ b/apis/README.md
@@ -0,0 +1,41 @@
+# Documentation for API integration
+
+## Import
+
+The API provider gets imported in the node_helper.js. As parameter it gets the config of the module.
+
+## Stations
+
+To display the data of the stations in the UI, a single station has to be in the following format:
+
+```
+{
+    "name": "Aral Tankstelle", // String
+    "prices": {  // Object
+        "diesel": 1.009, // Float
+        // "type": amount
+    },
+    "distance": 2.2, // Float
+    "isOpen": true, // Boolean
+    "address": "70376 Stuttgart - Pragstraße 138A", // String
+    "lat": 48.8075371, // Float
+    "lng": 9.194154, // Float
+}
+```
+
+## getData
+
+The API provider needs to implement the function `getData`, which gets a callback as parameter.
+The callback has to have the following format:
+
+```
+callback(null, {
+    types: ['diesel', 'e5', 'e10'], // Array | types supported by the API provider.
+    unit: 'km', // String | unit for the distance either in kilometres (km) or miles (ml).
+    currency: 'EUR', // String | curreny of the fuel prices either in EUR or USD.
+    byPrice: stations, // Array | stations (see above) sorted by price.
+    byDistance: distance // Array | stations (see above) sorted by distance.
+});
+```
+
+If an error occurs in the process you can return it as the first parameter of the callback.
diff --git a/apis/spritpreisrechner.js b/apis/spritpreisrechner.js
new file mode 100644
index 0000000..cb3865d
--- /dev/null
+++ b/apis/spritpreisrechner.js
@@ -0,0 +1,218 @@
+/**
+ * @file apis/spritpreisrechner.js
+ *
+ * @author fewieden
+ * @license MIT
+ *
+ * @see  https://github.com/fewieden/MMM-Fuel
+ */
+
+/**
+ * @external request
+ * @see https://www.npmjs.com/package/request
+ */
+const request = require('request');
+const Coordinate = require('./utils/Coordinate.js');
+
+/**
+ * @module apis/spritpreisrechner
+ * @description Queries data from spritpreisrechner.at
+ *
+ * @requires external:request
+ * @requires module:Coordinate
+ *
+ * @param {Object} config - Configuration.
+ * @param {number} config.lat - Latitude of Coordinate.
+ * @param {number} config.lng - Longitude of Coordinate.
+ * @param {int} config.radius - Lookup area for gas stations.
+ * @param {string} config.sortBy - Type to sort by price.
+ * @param {string[]} config.types - Requested fuel types.
+ * @param {boolean} config.showOpenOnly - Flag to show only open gas stations.
+ */
+module.exports = (config) => {
+    /** @member {string} baseUrl - API url */
+    const baseUrl = 'http://www.spritpreisrechner.at/espritmap-app/GasStationServlet';
+
+    /** @member {Object} types - Mapping of fuel types to API fuel types. */
+    const types = {
+        diesel: 'DIE',
+        e5: 'SUP',
+        gas: 'GAS'
+    };
+
+    /** @member {Object} topLeft - Top left corner of lookup area. */
+    const topLeft = Coordinate.from(config.lat, config.lng).to(315, config.radius);
+    /** @member {Object} bottomRight - Bottom right corner of lookup area. */
+    const bottomRight = Coordinate.to(135, config.radius);
+
+    /**
+     * @function generateOptions
+     * @description Helper function to generate API request options.
+     *
+     * @param {string} type - Fuel type
+     * @returns {Object} Options
+     */
+    const generateOptions = type => ({
+        url: baseUrl,
+        method: 'POST',
+        form: `data=${
+            encodeURI(
+                JSON.stringify(
+                    [
+                        config.showOpenOnly ? '' : 'checked',
+                        types[type],
+                        topLeft.lng,
+                        topLeft.lat,
+                        bottomRight.lng,
+                        bottomRight.lat
+                    ]
+                )
+            )
+        }`
+    });
+
+    /**
+     * @function requestFuelType
+     * @description API request for specified type.
+     *
+     * @param {string} type - Fuel type.
+     * @returns {Promise} Data or error message.
+     */
+    const requestFuelType = type => new Promise((resolve, reject) => {
+        request(generateOptions(type), (error, response, body) => {
+            if (response.statusCode === 200) {
+                resolve({ type, data: JSON.parse(body) });
+            }
+            reject(`Error getting fuel data ${response.statusCode}`);
+        });
+    });
+
+    /**
+     * @function compareStations
+     * @description Helper function to compare gas stations.
+     *
+     * @param {Object} a - Gas Station
+     * @param {Object} b - Gas Station
+     * @returns {boolean}
+     */
+    const compareStations = (a, b) => a.city === b.city &&
+        a.postalCode === b.postalCode &&
+        a.gasStationName === b.gasStationName &&
+        a.latitude === b.latitude &&
+        a.longitude === b.longitude;
+
+    /**
+     * @function reducePrice
+     * @description Reduces array of prices to single price.
+     *
+     * @param {Object[]} prices - All prices.
+     * @returns {number} Highest price or -1 if there is no price.
+     */
+    const reducePrice = prices => prices.reduce((current, price) => {
+        if (!Object.prototype.hasOwnProperty.call(price, 'amount') || price.amount === '') {
+            return current;
+        }
+        const newAmount = parseFloat(price.amount);
+        return current < newAmount ? newAmount : current;
+    }, -1);
+
+    /**
+     * @function filterStations
+     * @description Helper function to filter gas stations.
+     *
+     * @param {Object} station - Gas Station
+     * @returns {boolean}
+     */
+    const filterStations = (station) => {
+        const prices = Object.keys(station.prices);
+        return !prices.every(type => station.prices[type] === -1);
+    };
+
+    /**
+     * @function sortByDistance
+     * @description Helper function to sort gas stations by distance.
+     *
+     * @param {Object} a - Gas Station
+     * @param {Object} b - Gas Station
+     * @returns {number}
+     */
+    const sortByDistance = (a, b) => a.distance - b.distance;
+
+    /**
+     * @function normalizeStations
+     * @description Helper function to normalize the structure of gas stations for the UI.
+     *
+     * @param {Object[]} stations - Gas Station.
+     * @param {string[]} keys - Fuel types except config option sortBy.
+     *
+     * @see apis/README.md
+     */
+    const normalizeStations = (stations, keys) => {
+        stations.forEach((value, index) => {
+            /* eslint-disable no-param-reassign */
+            stations[index].name = value.gasStationName;
+            stations[index].prices = { [config.sortBy]: reducePrice(value.spritPrice) };
+            keys.forEach((type) => { stations[index].prices[type] = -1; });
+            stations[index].isOpen = value.open;
+            stations[index].address = `${value.postalCode} ${value.city} - ${value.address}`;
+            stations[index].lat = parseFloat(value.latitude);
+            stations[index].lng = parseFloat(value.longitude);
+            /* eslint-enable no-param-reassign */
+        });
+    };
+
+    return {
+        /**
+         * @callback getDataCallback
+         * @param {?string} error - Error message.
+         * @param {Object} data - API data.
+         *
+         * @see apis/README.md
+         */
+
+        /**
+         * @function getData
+         * @description Performs the data query and processing.
+         *
+         * @param {getDataCallback} callback - Callback that handles the API data.
+         */
+        getData(callback) {
+            Promise
+                .all(config.types.map(requestFuelType))
+                .then((responses) => {
+                    const collection = {};
+                    responses.forEach((element) => { collection[element.type] = element.data; });
+
+                    let stations = collection[config.sortBy];
+                    delete collection[config.sortBy];
+                    const keys = Object.keys(collection);
+
+                    normalizeStations(stations, keys);
+
+                    keys.forEach((type) => {
+                        collection[type].forEach((station) => {
+                            for (let i = 0; i < stations.length; i += 1) {
+                                if (compareStations(station, stations[i])) {
+                                    stations[i].prices[type] = reducePrice(station.spritPrice);
+                                    break;
+                                }
+                            }
+                        });
+                    });
+
+                    stations = stations.filter(filterStations);
+
+                    const distance = stations.slice(0);
+                    distance.sort(sortByDistance);
+
+                    callback(null, {
+                        types: ['diesel', 'e5', 'gas'],
+                        unit: 'km',
+                        currency: 'EUR',
+                        byPrice: stations,
+                        byDistance: distance
+                    });
+                });
+        }
+    };
+};
diff --git a/apis/tankerkoenig.js b/apis/tankerkoenig.js
new file mode 100644
index 0000000..d71f2c6
--- /dev/null
+++ b/apis/tankerkoenig.js
@@ -0,0 +1,141 @@
+/**
+ * @file apis/tankerkoenig.js
+ *
+ * @author fewieden
+ * @license MIT
+ *
+ * @see  https://github.com/fewieden/MMM-Fuel
+ */
+
+/**
+ * @external request
+ * @see https://www.npmjs.com/package/request
+ */
+const request = require('request');
+
+/**
+ * @module apis/tankerkoenig
+ * @description Queries data from tankerkoenig.de
+ *
+ * @requires external:request
+ *
+ * @param {Object} config - Configuration.
+ * @param {number} config.lat - Latitude of Coordinate.
+ * @param {number} config.lng - Longitude of Coordinate.
+ * @param {int} config.radius - Lookup area for gas stations.
+ * @param {string} config.sortBy - Type to sort by price.
+ * @param {string[]} config.types - Requested fuel types.
+ * @param {boolean} config.showOpenOnly - Flag to show only open gas stations.
+ *
+ * @see https://creativecommons.tankerkoenig.de/
+ */
+module.exports = (config) => {
+    /** @member {string} baseUrl - API url */
+    const baseUrl = 'https://creativecommons.tankerkoenig.de/json/list.php';
+
+    /** @member {Object} options - API url combined with config options. */
+    const options = {
+        url: `${baseUrl}?lat=${config.lat}&lng=${config.lng}&rad=${config.radius}&type=all&apikey=${
+            config.api_key}&sort=dist`
+    };
+
+    /**
+     * @function sortByPrice
+     * @description Helper function to sort gas stations by price.
+     *
+     * @param {Object} a - Gas Station
+     * @param {Object} b - Gas Station
+     * @returns {number}
+     */
+    const sortByPrice = (a, b) => {
+        if (b[config.sortBy] === 0) {
+            return Number.MIN_SAFE_INTEGER;
+        } else if (a[config.sortBy] === 0) {
+            return Number.MAX_SAFE_INTEGER;
+        }
+        return a[config.sortBy] - b[config.sortBy];
+    };
+
+    /**
+     * @function filterStations
+     * @description Helper function to filter gas stations.
+     *
+     * @param {Object} station - Gas Station
+     * @returns {boolean}
+     */
+    const filterStations = (station) => {
+        for (let i = 0; i < config.types.length; i += 1) {
+            if (station[config.types[i]] <= 0 || (config.showOpenOnly && !station.isOpen)) {
+                return false;
+            }
+        }
+        return true;
+    };
+
+    /**
+     * @function normalizeStations
+     * @description Helper function to normalize the structure of gas stations for the UI.
+     *
+     * @param {Object} value - Gas Station
+     * @param {int} index - Array index
+     * @param {Object[]} stations - Original Array.
+     *
+     * @see apis/README.md
+     */
+    const normalizeStations = (value, index, stations) => {
+        /* eslint-disable no-param-reassign */
+        stations[index].prices = {
+            diesel: value.diesel,
+            e5: value.e5,
+            e10: value.e10
+        };
+        stations[index].distance = value.dist;
+        stations[index].address = `${(`0${value.postCode}`).slice(-5)} ${
+            value.place} - ${value.street} ${value.houseNumber}`;
+        /* eslint-enable no-param-reassign */
+    };
+
+    return {
+        /**
+         * @callback getDataCallback
+         * @param {?string} error - Error message.
+         * @param {Object} data - API data.
+         *
+         * @see apis/README.md
+         */
+
+        /**
+         * @function getData
+         * @description Performs the data query and processing.
+         *
+         * @param {getDataCallback} callback - Callback that handles the API data.
+         */
+        getData(callback) {
+            request(options, (error, response, body) => {
+                if (response.statusCode === 200) {
+                    const parsedBody = JSON.parse(body);
+                    if (parsedBody.ok) {
+                        const stations = parsedBody.stations.filter(filterStations);
+
+                        stations.forEach(normalizeStations);
+
+                        const price = stations.slice(0);
+                        price.sort(sortByPrice);
+
+                        callback(null, {
+                            types: ['diesel', 'e5', 'e10'],
+                            unit: 'km',
+                            currency: 'EUR',
+                            byPrice: price,
+                            byDistance: stations
+                        });
+                    } else {
+                        callback('Error no fuel data');
+                    }
+                } else {
+                    callback(`Error getting fuel data ${response.statusCode}`);
+                }
+            });
+        }
+    };
+};
diff --git a/apis/utils/Coordinate.js b/apis/utils/Coordinate.js
new file mode 100644
index 0000000..6774922
--- /dev/null
+++ b/apis/utils/Coordinate.js
@@ -0,0 +1,88 @@
+/**
+ * @file apis/utils/Coordinate.js
+ *
+ * @author fewieden
+ * @license MIT
+ *
+ * @see  https://github.com/fewieden/MMM-Fuel
+ */
+
+/**
+ * Earth radius in meter.
+ * @type {number}
+ */
+const earth = 6371e3;
+
+/**
+ * @function deg2rad
+ * @description Converts degree to radian.
+ *
+ * @param {number} degree - Value to convert.
+ * @returns {number} Converted value.
+ */
+const deg2rad = degree => degree * (Math.PI / 180);
+
+/**
+ * @function rad2deg
+ * @description Converts radian to degree.
+ *
+ * @param {number} rad - Value to convert.
+ * @returns {number} Converted value.
+ */
+const rad2deg = rad => rad * (180 / Math.PI);
+
+/**
+ * @module apis/utils/Coordinate
+ * @description Utility to calculate target Coordinate based of a start Coordinate.
+ */
+module.exports = {
+
+    /**
+     * @function from
+     * @description Sets the start Coordinate.
+     *
+     * @param {number} lat - Latitude of a Coordinate
+     * @param {number} lng - Longitude of a Coordinate
+     * @returns {module:Coordinate}
+     */
+    from(lat, lng) {
+        this.lat = lat;
+        this.lng = lng;
+        return this;
+    },
+
+    /**
+     * @function to
+     * @description Calculates the target Coordinate.
+     *
+     * @param {number} degree - Direction to the target (North is 0).
+     * @param {number} distance - Distance in kilometres to the target.
+     * @returns {Object.<string, number>} Target Coordinate.
+     *
+     * @see https://github.com/chrisveness/geodesy
+     */
+    to(degree, distance) {
+        const radius = distance * 1000;
+
+        const δ = Math.sqrt(2 * (radius * radius)) / earth;
+        const θ = deg2rad(Number(degree));
+
+        const φ1 = deg2rad(this.lat);
+        const λ1 = deg2rad(this.lng);
+
+        const sinφ1 = Math.sin(φ1);
+        const cosφ1 = Math.cos(φ1);
+        const sinδ = Math.sin(δ);
+        const cosδ = Math.cos(δ);
+        const sinθ = Math.sin(θ);
+        const cosθ = Math.cos(θ);
+
+        const sinφ2 = (sinφ1 * cosδ) + (cosφ1 * sinδ * cosθ);
+        const φ2 = Math.asin(sinφ2);
+        const y = sinθ * sinδ * cosφ1;
+        const x = cosδ - (sinφ1 * sinφ2);
+        const λ2 = λ1 + Math.atan2(y, x);
+
+        return { lat: rad2deg(φ2), lng: ((rad2deg(λ2) + 540) % 360) - 180 };
+    }
+};
diff --git a/jsdoc.json b/jsdoc.json
new file mode 100644
index 0000000..292650e
--- /dev/null
+++ b/jsdoc.json
@@ -0,0 +1,19 @@
+{
+  "tags": {
+    "dictionaries": ["jsdoc"]
+  },
+  "source": {
+    "include": [
+      "package.json",
+      "README.md"
+    ],
+    "exclude": [
+      "node_modules"
+    ]
+  },
+  "opts": {
+    "destination": "docs",
+    "recurse": true
+  }
+
+}
diff --git a/node_helper.js b/node_helper.js
index c15912b..51e7855 100644
--- a/node_helper.js
+++ b/node_helper.js
@@ -1,71 +1,76 @@
-/* Magic Mirror
- * Module: MMM-Fuel
+/**
+ * @file node_helper.js
  *
- * By fewieden https://github.com/fewieden/MMM-Fuel
- * MIT Licensed.
+ * @author fewieden
+ * @license MIT
+ *
+ * @see  https://github.com/fewieden/MMM-Fuel
  */
 
-/* eslint-env node */
-/* eslint-disable no-console */
-
-const request = require('request');
+/**
+ * @external node_helper
+ * @see https://github.com/MichMich/MagicMirror/blob/master/modules/node_modules/node_helper/index.js
+ */
 const NodeHelper = require('node_helper');
 
-module.exports = NodeHelper.create({
+/**
+ * @external fs
+ * @see https://nodejs.org/api/fs.html
+ */
+const fs = require('fs');
 
-    baseUrl: 'https://creativecommons.tankerkoenig.de/json/list.php',
+/**
+ * @module node_helper
+ * @description Backend for the module to query data from the API providers.
+ *
+ * @requires external:fs
+ * @requires external:node_helper
+ */
+module.exports = NodeHelper.create({
 
+    /**
+     * @function start
+     * @description Logs a start message to the console.
+     * @override
+     */
     start() {
-        console.log(`Starting module: ${this.name}`);
+        console.log(`Starting module helper: ${this.name}`);
     },
 
+    /**
+     * @function socketNotificationReceived
+     * @description Receives socket notifications from the module.
+     * @override
+     *
+     * @param {string} notification - Notification name
+     * @param {*} payload - Detailed payload of the notification.
+     */
     socketNotificationReceived(notification, payload) {
         if (notification === 'CONFIG') {
             this.config = payload;
-            this.getData();
-            setInterval(() => {
+            if (fs.existsSync(`modules/${this.name}/apis/${this.config.provider}.js`)) {
+                // eslint-disable-next-line global-require, import/no-dynamic-require
+                this.provider = require(`./apis/${this.config.provider}`)(this.config);
                 this.getData();
-            }, this.config.updateInterval);
+                setInterval(() => {
+                    this.getData();
+                }, this.config.updateInterval);
+            } else {
+                console.log(`${this.name}: Couldn't load provider ${this.config.provider}`);
+            }
         }
     },
 
+    /**
+     * @function getData
+     * @description Uses API provider to get data.
+     */
     getData() {
-        const options = {
-            url: `${this.baseUrl}?lat=${this.config.lat}&lng=${this.config.lng}&rad=${this.config.radius
-                }&type=all&apikey=${this.config.api_key}&sort=dist`
-        };
-        request(options, (error, response, body) => {
-            if (response.statusCode === 200) {
-                const parsedBody = JSON.parse(body);
-                if (parsedBody.ok) {
-                    for (let i = parsedBody.stations.length - 1; i >= 0; i -= 1) {
-                        let removeFlag = false;
-                        for (let n = 0; n < this.config.types.length; n += 1) {
-                            if (parsedBody.stations[i][this.config.types[n]] <= 0 ||
-                                (this.config.showOpenOnly && !parsedBody.stations[i].isOpen)) {
-                                removeFlag = true;
-                                break;
-                            }
-                        }
-                        if (removeFlag) {
-                            parsedBody.stations.splice(i, 1);
-                        }
-                    }
-                    const price = parsedBody.stations.slice(0);
-                    price.sort((a, b) => {
-                        if (b[this.config.sortBy] === 0) {
-                            return Number.MIN_SAFE_INTEGER;
-                        } else if (a[this.config.sortBy] === 0) {
-                            return Number.MAX_SAFE_INTEGER;
-                        }
-                        return a[this.config.sortBy] - b[this.config.sortBy];
-                    });
-                    this.sendSocketNotification('PRICELIST', { byPrice: price, byDistance: parsedBody.stations });
-                } else {
-                    console.log('Error no fuel data');
-                }
+        this.provider.getData((err, data) => {
+            if (err) {
+                console.log(err);
             } else {
-                console.log(`Error getting fuel data ${response.statusCode}`);
+                this.sendSocketNotification('PRICELIST', data);
             }
         });
     }
diff --git a/package.json b/package.json
index ebacb07..b01c890 100644
--- a/package.json
+++ b/package.json
@@ -1,9 +1,10 @@
 {
   "name": "mmm-fuel",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "Gas Station price Module for MagicMirror2",
   "scripts": {
-    "lint": "./node_modules/.bin/eslint . && ./node_modules/.bin/stylelint ."
+    "lint": "./node_modules/.bin/eslint . && ./node_modules/.bin/stylelint .",
+    "docs": "./node_modules/.bin/jsdoc -c jsdoc.json ."
   },
   "repository": {
     "type": "git",
@@ -24,6 +25,7 @@
     "eslint": "^3.14.1",
     "eslint-config-airbnb-base": "^11.0.1",
     "eslint-plugin-import": "^2.2.0",
+    "jsdoc": "^3.4.3",
     "stylelint": "^7.8.0",
     "stylelint-config-standard": "^16.0.0"
   },