diff --git a/.gitignore b/.gitignore
index f06250660..1a010882b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 /composer.phar
 .DS_Store
 /.eslintcache
+/tests/selenium/log
diff --git a/package.json b/package.json
index aa8eec7bc..4848b045c 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,9 @@
 	"private": true,
 	"scripts": {
 		"test": "grunt test && npm run doc && dev-scripts/svg_check.sh",
-		"doc": "jsdoc -c jsdoc.json"
+		"doc": "jsdoc -c jsdoc.json",
+		"selenium-test-cucumber": "wdio tests/selenium/wdio.conf.cucumber.js",
+		"selenium-test": "wdio tests/selenium/wdio.conf.js"
 	},
 	"dependencies": {},
 	"devDependencies": {
@@ -15,8 +17,13 @@
 		"grunt-notify": "0.4.5",
 		"grunt-stylelint": "0.10.1",
 		"jsdoc": "3.5.5",
+		"mwbot": "1.0.10",
 		"pre-commit": "1.2.2",
 		"stylelint-config-wikimedia": "0.5.0",
-		"svgo": "0.7.2"
+		"svgo": "0.7.2",
+		"wdio-cucumber-framework": "1.1.1",
+		"wdio-mediawiki": "0.2.0",
+		"wdio-spec-reporter": "0.1.4",
+		"webdriverio": "4.13.1"
 	}
 }
diff --git a/tests/selenium/.eslintrc.json b/tests/selenium/.eslintrc.json
new file mode 100644
index 000000000..21fbae785
--- /dev/null
+++ b/tests/selenium/.eslintrc.json
@@ -0,0 +1,18 @@
+{
+	"root": true,
+	"extends": [
+		"wikimedia/server"
+	],
+	"env": {
+		"mocha": true
+	},
+	"globals": {
+		"browser": false,
+		"$": "readonly",
+		"mw": false
+	},
+	"rules": {
+		"camelcase": "off",
+		"no-restricted-syntax": "off"
+	}
+}
diff --git a/tests/selenium/README.md b/tests/selenium/README.md
new file mode 100644
index 000000000..5c7d7c1b3
--- /dev/null
+++ b/tests/selenium/README.md
@@ -0,0 +1,42 @@
+# Selenium tests
+
+Please see tests/selenium/README.md file in mediawiki/core repository, usually at mediawiki/vagrant/mediawiki folder.
+
+## Setup
+
+Set up MediaWiki-Vagrant:
+
+    cd mediawiki/vagrant
+    vagrant up
+    vagrant roles enable minerva
+    vagrant provision
+    cd mediawiki
+    npm install
+
+## Start Chromedriver and run all tests
+
+Run both mediawiki/core and extension tests from mediawiki/core repository (usually at mediawiki/vagrant/mediawiki folder):
+
+    npm run selenium
+
+## Start Chromedriver
+
+To run only some tests, you first have to start Chromedriver in one terminal tab (or window):
+
+    chromedriver --url-base=wd/hub --port=4444
+
+## Run test(s) from one file
+
+Then, in another terminal tab (or window) run this from mediawiki/core repository (usually at mediawiki/vagrant/mediawiki folder):
+
+    npm run selenium-test -- --spec tests/selenium/specs/FILE-NAME.js
+
+`wdio` is a dependency of mediawiki/core that you have installed with `npm install`.
+
+## Run specific test(s)
+
+To run only test(s) which name contains string TEST-NAME, run this from mediawiki/core repository (usually at mediawiki/vagrant/mediawiki folder):
+
+    ./node_modules/.bin/wdio tests/selenium/wdio.conf.js --spec extensions/EXTENSION-NAME/tests/selenium/specs/FILE-NAME.js --mochaOpts.grep TEST-NAME
+
+Make sure Chromedriver is running when executing the above command.
diff --git a/tests/selenium/features/category.feature b/tests/selenium/features/category.feature
new file mode 100644
index 000000000..9916cea46
--- /dev/null
+++ b/tests/selenium/features/category.feature
@@ -0,0 +1,10 @@
+Feature: Categories
+
+  Scenario: I can view categories
+    Given I am in a wiki that has categories
+      And I am using the mobile site
+      And I am in beta mode
+      And I am on the "Selenium categories test page" page
+    When I click on the category button
+    Then I should see the categories overlay
+      And I should see a list of categories
diff --git a/tests/selenium/features/step_definitions/category_steps.js b/tests/selenium/features/step_definitions/category_steps.js
new file mode 100644
index 000000000..ee9e479e1
--- /dev/null
+++ b/tests/selenium/features/step_definitions/category_steps.js
@@ -0,0 +1,24 @@
+const assert = require( 'assert' ),
+	{ ArticlePage } = require( './../support/world' );
+
+const iClickOnTheCategoryButton = () => {
+	ArticlePage.category_element.waitForExist();
+	ArticlePage.category_element.click();
+};
+
+const iShouldSeeTheCategoriesOverlay = () => {
+	ArticlePage.overlay_heading_element.waitForExist();
+	assert.strictEqual( ArticlePage.overlay_heading_element.getText(),
+		'Categories' );
+};
+
+const iShouldSeeAListOfCategories = () => {
+	const el = ArticlePage.overlay_category_topic_item_element.waitForVisible();
+	assert.strictEqual( el, true );
+};
+
+module.exports = {
+	iClickOnTheCategoryButton,
+	iShouldSeeTheCategoriesOverlay,
+	iShouldSeeAListOfCategories
+};
diff --git a/tests/selenium/features/step_definitions/common_steps.js b/tests/selenium/features/step_definitions/common_steps.js
new file mode 100644
index 000000000..b41fb1cf7
--- /dev/null
+++ b/tests/selenium/features/step_definitions/common_steps.js
@@ -0,0 +1,31 @@
+const assert = require( 'assert' ),
+	{ ArticlePage, UserLoginPage } = require( '../support/world' );
+
+const iAmUsingTheMobileSite = () => {
+	ArticlePage.setMobileMode();
+};
+
+const iAmInBetaMode = () => {
+	ArticlePage.setBetaMode();
+};
+
+const iAmOnPage = ( article ) => {
+	ArticlePage.open( article );
+};
+
+const iAmLoggedIn = () => {
+	UserLoginPage.open();
+	UserLoginPage.loginAdmin();
+	assert.strictEqual( ArticlePage.is_authenticated_element.isExisting(), true );
+};
+
+const iAmLoggedIntoTheMobileWebsite = () => {
+	iAmUsingTheMobileSite();
+	iAmLoggedIn();
+};
+
+module.exports = {
+	iAmLoggedIntoTheMobileWebsite,
+	iAmUsingTheMobileSite,
+	iAmLoggedIn, iAmOnPage, iAmInBetaMode
+};
diff --git a/tests/selenium/features/step_definitions/create_page_api_steps.js b/tests/selenium/features/step_definitions/create_page_api_steps.js
new file mode 100644
index 000000000..8e035e104
--- /dev/null
+++ b/tests/selenium/features/step_definitions/create_page_api_steps.js
@@ -0,0 +1,52 @@
+const { api } = require( '../support/world' ),
+	Api = require( 'wdio-mediawiki/Api' );
+
+const login = () => {
+	return api.loginGetEditToken( {
+		username: browser.options.username,
+		password: browser.options.password,
+		apiUrl: `${browser.options.baseUrl}/api.php`
+	} );
+};
+
+const waitForPropagation = ( timeMs ) => {
+	// wait 2 seconds so the change can propogate.
+	const d = new Date();
+	browser.waitUntil( () => new Date() - d > timeMs );
+};
+
+const iAmInAWikiThatHasCategories = ( title ) => {
+	const msg = 'This page is used by Selenium to test category related features.',
+		summary = 'edit by selenium test',
+		wikitext = `
+            ${msg}
+
+            [[Category:Test category]]
+            [[Category:Selenium artifacts]]
+            [[Category:Selenium hidden category]]
+        `;
+
+	login().then( () => api.batch( [
+		[ 'create', 'Category:Selenium artifacts', msg, summary ],
+		[ 'create', 'Category:Test category', msg, summary ],
+		[ 'create', 'Category:Selenium hidden category', '__HIDDENCAT__', summary ]
+	] ) )
+		.catch( ( err ) => {
+			if ( err.code === 'articleexists' ) {
+				return;
+			}
+			throw err;
+		} );
+
+	// A pause is necessary to let the categories register with database before trying to use
+	// them in an article
+	waitForPropagation( 5000 );
+	Api.edit( title, wikitext );
+	// categories are handled by a JobRunner so need extra time to appear via API calls!
+	waitForPropagation( 5000 );
+};
+
+module.exports = {
+	waitForPropagation,
+	iAmInAWikiThatHasCategories
+};
diff --git a/tests/selenium/features/step_definitions/history_steps.js b/tests/selenium/features/step_definitions/history_steps.js
new file mode 100644
index 000000000..00551a0d4
--- /dev/null
+++ b/tests/selenium/features/step_definitions/history_steps.js
@@ -0,0 +1,12 @@
+const assert = require( 'assert' ),
+	{ ArticlePage, SpecialHistoryPage } = require( '../support/world' );
+
+const iClickOnTheHistoryLinkInTheLastModifiedBar = () => {
+	ArticlePage.last_modified_bar_history_link_element.waitForVisible();
+	ArticlePage.last_modified_bar_history_link_element.click();
+	assert.strictEqual( SpecialHistoryPage.side_list_element.isVisible(), true );
+};
+
+module.exports = {
+	iClickOnTheHistoryLinkInTheLastModifiedBar
+};
diff --git a/tests/selenium/features/step_definitions/index.js b/tests/selenium/features/step_definitions/index.js
new file mode 100644
index 000000000..2270d28d3
--- /dev/null
+++ b/tests/selenium/features/step_definitions/index.js
@@ -0,0 +1,41 @@
+const { defineSupportCode } = require( 'cucumber' ),
+	{ iClickOnTheCategoryButton,
+		iShouldSeeTheCategoriesOverlay, iShouldSeeAListOfCategories
+	} = require( './category_steps' ),
+	{ iAmInAWikiThatHasCategories } = require( './create_page_api_steps' ),
+	{
+		iAmUsingTheMobileSite,
+		iAmLoggedIntoTheMobileWebsite,
+		iAmOnPage, iAmInBetaMode
+	} = require( './common_steps' ),
+	{
+		iClickOnTheHistoryLinkInTheLastModifiedBar
+	} = require( './history_steps' );
+
+defineSupportCode( function ( { Then, When, Given } ) {
+
+	// common steps
+	Given( /^I am using the mobile site$/, iAmUsingTheMobileSite );
+
+	Given( /^I am in beta mode$/, iAmInBetaMode );
+
+	Given( /^I am on the "(.+)" page$/, iAmOnPage );
+
+	Given( /^I am logged into the mobile website$/, iAmLoggedIntoTheMobileWebsite );
+
+	// Page steps
+	Given( /^I am in a wiki that has categories$/, () => {
+		iAmInAWikiThatHasCategories( 'Selenium categories test page' );
+	} );
+
+	// history steps
+	When( /^I click on the history link in the last modified bar$/,
+		iClickOnTheHistoryLinkInTheLastModifiedBar );
+
+	// Category steps
+	When( /^I click on the category button$/, iClickOnTheCategoryButton );
+
+	Then( /^I should see the categories overlay$/, iShouldSeeTheCategoriesOverlay );
+
+	Then( /^I should see a list of categories$/, iShouldSeeAListOfCategories );
+} );
diff --git a/tests/selenium/features/support/hooks.js b/tests/selenium/features/support/hooks.js
new file mode 100644
index 000000000..5affbc5cd
--- /dev/null
+++ b/tests/selenium/features/support/hooks.js
@@ -0,0 +1,22 @@
+/**
+ * Hooks
+ *
+ * Hooks are used for setup and teardown of the environment before and after each scenario.
+ * It's preferable to use tags to invoke hooks rather than using the generic 'Before' and 'After'
+ * events, which execute before and after all scenario.
+ * https://github.com/cucumber/cucumber-js/blob/master/docs/support_files/hooks.md
+ */
+
+const { After, Before } = require( 'cucumber' );
+
+Before( function () {
+	// This hook will be executed before ALL scenarios
+} );
+
+After( function () {
+	// This hook will be executed after ALL scenarios
+} );
+
+Before( { tags: '@foo' }, function () {
+	// This hook will be executed before scenarios tagged with @foo
+} );
diff --git a/tests/selenium/features/support/pages/article_page.js b/tests/selenium/features/support/pages/article_page.js
new file mode 100644
index 000000000..4518489ea
--- /dev/null
+++ b/tests/selenium/features/support/pages/article_page.js
@@ -0,0 +1,21 @@
+/**
+ * Represents a generic article page
+ *
+ * @extends MinervaPage
+ * @example
+ * https://en.m.wikipedia.org/wiki/Barack_Obama
+ */
+
+const MinervaPage = require( './minerva_page' );
+
+class ArticlePage extends MinervaPage {
+
+	get category_element() { return $( '.category-button' ); }
+	get overlay_heading_element() { return $( '.overlay-title h2' ); }
+	get overlay_category_topic_item_element() { return $( '.topic-title-list li' ); }
+	get is_authenticated_element() { return $( 'body.is-authenticated' ); }
+	get last_modified_bar_history_link_element() { return $( '.last-modifier-tagline a[href*=\'Special:History\']' ); }
+
+}
+
+module.exports = new ArticlePage();
diff --git a/tests/selenium/features/support/pages/minerva_page.js b/tests/selenium/features/support/pages/minerva_page.js
new file mode 100644
index 000000000..8feeb9ab6
--- /dev/null
+++ b/tests/selenium/features/support/pages/minerva_page.js
@@ -0,0 +1,67 @@
+/**
+ * Represents a page the can be presented in desktop
+ * or mobile mode (requires mobilefrontend), and has
+ * features like public 'beta' mode (requires mobilefrontend).
+ *
+ * @extends Page
+ * @example
+ * https://en.m.wikipedia.org/wiki/Barack_Obama
+ */
+
+const { Page } = require( './mw_core_pages' );
+
+class MinervaPage extends Page {
+
+	get title() { return browser.getTitle(); }
+
+	/**
+	 * Opens a page if it isn't already open.
+	 * @param {string} path
+	 */
+	open( path = 'Main_Page' ) {
+		const currentPage = browser.getUrl(),
+			newPage = browser.options.baseUrl + '/index.php?title=' + path;
+		if ( currentPage !== newPage ) {
+			browser.url( newPage );
+		}
+	}
+
+	/**
+	 * Ensure browser is opened on a MediaWiki page, and set a specified
+	 * cookie for that domain.
+	 * @param {string} name - name of the cookie
+	 * @param {string} value - value of the cookie
+	 */
+	setCookie( name, value ) {
+		const currentPage = browser.getUrl();
+		let cookie;
+		if ( !currentPage.includes( browser.options.baseUrl ) ) {
+			this.open();
+		}
+
+		cookie = browser.getCookie( name );
+
+		if ( !cookie || cookie.value !== value ) {
+			browser.setCookie( {
+				name: name,
+				value: value } );
+		}
+	}
+
+	/**
+	 * Set the mobile cookie
+	 */
+	setMobileMode() {
+		this.setCookie( 'mf_useformat', 'true' );
+	}
+
+	/**
+	 * Set the beta cookie
+	 */
+	setBetaMode() {
+		this.setCookie( 'optin', 'beta' );
+	}
+
+}
+
+module.exports = MinervaPage;
diff --git a/tests/selenium/features/support/pages/minerva_pages.js b/tests/selenium/features/support/pages/minerva_pages.js
new file mode 100644
index 000000000..4fc39edd9
--- /dev/null
+++ b/tests/selenium/features/support/pages/minerva_pages.js
@@ -0,0 +1,7 @@
+/**
+ * A list of all custom Minerva pageObjects.
+ * To simplify imports in world.js.
+ */
+module.exports = {
+	ArticlePage: require( './article_page' )
+};
diff --git a/tests/selenium/features/support/pages/mw_core_pages.js b/tests/selenium/features/support/pages/mw_core_pages.js
new file mode 100644
index 000000000..c33f858da
--- /dev/null
+++ b/tests/selenium/features/support/pages/mw_core_pages.js
@@ -0,0 +1,9 @@
+/**
+ * A list of all MediaWiki core pageObjects.
+ * To simplify imports in world.js.
+ */
+module.exports = {
+	// Page is a constructor, all other pageObjects are instances.
+	Page: require( '../../../../../../../tests/selenium/pageobjects/page.js' ),
+	UserLoginPage: require( '../../../../../../../tests/selenium/pageobjects/userlogin.page.js' )
+};
diff --git a/tests/selenium/features/support/world.js b/tests/selenium/features/support/world.js
new file mode 100644
index 000000000..30266eab2
--- /dev/null
+++ b/tests/selenium/features/support/world.js
@@ -0,0 +1,30 @@
+/**
+ * World
+ *
+ * World is a function that is bound as `this` to each step of a scenario.
+ * It is reset for each scenario.
+ * https://github.com/cucumber/cucumber-js/blob/master/docs/support_files/world.md
+ *
+ * Contrary to Cucumber.js best practices, this `MinervaWorld` is not being
+ * bound to scenarios with the `setWorldConstructor` like this:
+ *
+ * setWorldConstructor(MinervaWorld);
+ *
+ * Instead, it acts as a simple function that encapsulates all dependencies,
+ * and is exported so that it can be imported into each step definition file,
+ * allowing us to use the dependencies across scenarios.
+ */
+
+const MwBot = require( 'mwbot' ),
+	mwCorePages = require( '../support/pages/mw_core_pages' ),
+	minervaPages = require( '../support/pages/minerva_pages' );
+
+function MinervaWorld() {
+	/* dependencies */
+	this.api = new MwBot();
+	/* pageObjects */
+	Object.assign( this, mwCorePages );
+	Object.assign( this, minervaPages );
+}
+
+module.exports = new MinervaWorld();
diff --git a/tests/selenium/specs/category.js b/tests/selenium/specs/category.js
new file mode 100644
index 000000000..64faf252d
--- /dev/null
+++ b/tests/selenium/specs/category.js
@@ -0,0 +1,46 @@
+const { iClickOnTheCategoryButton,
+		iShouldSeeTheCategoriesOverlay,
+		iShouldSeeAListOfCategories
+	} = require( '../features/step_definitions/category_steps' ),
+	{
+		iAmInAWikiThatHasCategories
+	} = require( '../features/step_definitions/create_page_api_steps' ),
+	{
+		iAmUsingTheMobileSite,
+		iAmOnPage, iAmInBetaMode
+	} = require( '../features/step_definitions/common_steps' );
+
+// Feature: Categories
+describe( 'Categories', function () {
+	// Scenario: I can view categories
+	it( 'I can view categories', function () {
+		const title = 'Selenium categories test page';
+		// Given I am in a wiki that has categories
+		iAmInAWikiThatHasCategories( title );
+
+		// And I am using the mobile site
+		iAmUsingTheMobileSite();
+
+		// And I am in beta mode
+		iAmInBetaMode();
+
+		// And I am on the "Selenium categories test page" page
+		iAmOnPage( title );
+
+		// When I click on the category button
+		iClickOnTheCategoryButton();
+
+		// Then I should see the categories overlay
+		iShouldSeeTheCategoriesOverlay();
+
+		// FIXME: This check is partially skipped as there is no way to lower $wgJobRunRate
+		// See: T199939#5095838
+		try {
+			iShouldSeeAListOfCategories();
+		} catch ( e ) {
+			// pass.
+			// eslint-disable-next-line no-console
+			console.warn( 'Unable to check the list of the categories. Is wgJobRunRate set correctly?' );
+		}
+	} );
+} );
diff --git a/tests/selenium/wdio.conf.cucumber.js b/tests/selenium/wdio.conf.cucumber.js
new file mode 100644
index 000000000..80db4d803
--- /dev/null
+++ b/tests/selenium/wdio.conf.cucumber.js
@@ -0,0 +1,14 @@
+const { config } = require( './wdio.conf' );
+
+config.specs = [ __dirname + '/features/*.feature' ];
+config.framework = 'cucumber';
+config.cucumberOpts = {
+	require: [
+		'./tests/selenium/features/support/*.js',
+		'./tests/selenium/features/step_definitions/index.js'
+		// search a (sub)folder for JS files with a wildcard
+		// works since version 1.1 of the wdio-cucumber-framework
+		// './src/**/*.js',
+	]
+};
+exports.config = config;
diff --git a/tests/selenium/wdio.conf.js b/tests/selenium/wdio.conf.js
new file mode 100644
index 000000000..89a4baff0
--- /dev/null
+++ b/tests/selenium/wdio.conf.js
@@ -0,0 +1,95 @@
+/**
+ * See also: http://webdriver.io/guide/testrunner/configurationfile.html
+ */
+const fs = require( 'fs' ),
+	saveScreenshot = require( 'wdio-mediawiki' ).saveScreenshot;
+
+exports.config = {
+	// ======
+	// Custom WDIO config specific to MediaWiki
+	// ======
+	// Use in a test as `browser.options.<key>`.
+	// Defaults are for convenience with MediaWiki-Vagrant
+
+	// Wiki admin
+	username: process.env.MEDIAWIKI_USER || 'Admin',
+	password: process.env.MEDIAWIKI_PASSWORD || 'vagrant',
+
+	// Base for browser.url() and Page#openTitle()
+	baseUrl: ( process.env.MW_SERVER || 'http://127.0.0.1:8080' ) + (
+		process.env.MW_SCRIPT_PATH || '/w'
+	),
+
+	// ==================
+	// Test Files
+	// ==================
+	specs: [
+		__dirname + '/specs/*.js'
+	],
+
+	// ============
+	// Capabilities
+	// ============
+	capabilities: [ {
+		// https://sites.google.com/a/chromium.org/chromedriver/capabilities
+		browserName: 'chrome',
+		maxInstances: 1,
+		chromeOptions: {
+			// If DISPLAY is set, assume developer asked non-headless or CI with Xvfb.
+			// Otherwise, use --headless (added in Chrome 59)
+			// https://chromium.googlesource.com/chromium/src/+/59.0.3030.0/headless/README.md
+			args: [
+				...( process.env.DISPLAY ? [] : [ '--headless' ] ),
+				// Chrome sandbox does not work in Docker
+				...( fs.existsSync( '/.dockerenv' ) ? [ '--no-sandbox' ] : [] )
+			]
+		}
+	} ],
+
+	// ===================
+	// Test Configurations
+	// ===================
+
+	// Level of verbosity: silent | verbose | command | data | result | error
+	logLevel: 'error',
+
+	// Setting this enables automatic screenshots for when a browser command fails
+	// It is also used by afterTest for capturig failed assertions.
+	screenshotPath: process.env.LOG_DIR || __dirname + '/log',
+
+	// Default timeout for each waitFor* command.
+	waitforTimeout: 10 * 1000,
+
+	// See also: http://webdriver.io/guide/testrunner/reporters.html
+	reporters: [ 'spec' ],
+
+	// See also: http://mochajs.org
+	mochaOpts: {
+		ui: 'bdd',
+		timeout: 60 * 1000
+	},
+
+	// Make sure you have the wdio adapter package for the specific framework
+	// installed before running any tests.
+	framework: 'mocha',
+
+	// =====
+	// Hooks
+	// =====
+
+	/**
+	 * Save a screenshot when test fails.
+	 *
+	 * @param {Object} test Mocha Test object
+	 */
+	afterTest: function ( test ) {
+		var filePath;
+		if ( !test.passed ) {
+			filePath = saveScreenshot( test.title );
+			// eslint-disable-next-line no-console
+			console.log( '\n\tScreenshot: ' + filePath + '\n' );
+		}
+	}
+};
+
+module.exports = exports;