diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b72195b52..302f2a104 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -10,13 +10,13 @@ jobs:
           - ubuntu-latest
           - windows-latest
         browser:
-          - ChromeHeadless
-          - FirefoxHeadless
+          - chrome
+          - firefox
         include:
           - os: macos-latest
-            browser: Safari
+            browser: safari
           - os: windows-latest
-            browser: EdgeHeadless
+            browser: edge
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 13b1a32a4..f6050b14b 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -78,8 +78,6 @@ export default [
             globals: {
                 ...globals.node,
                 ...globals.mocha,
-                sinon: false,
-                expect: false,
             }
         },
         rules: {
diff --git a/karma.conf.js b/karma.conf.js
deleted file mode 100644
index 54380ebd2..000000000
--- a/karma.conf.js
+++ /dev/null
@@ -1,92 +0,0 @@
-// Karma configuration
-
-// The Safari launcher is broken, so construct our own
-function SafariBrowser(id, baseBrowserDecorator, args) {
-  baseBrowserDecorator(this);
-
-  this._start = function(url) {
-    this._execCommand('/usr/bin/open', ['-W', '-n', '-a', 'Safari', url]);
-  }
-}
-
-SafariBrowser.prototype = {
-  name: 'Safari'
-}
-
-module.exports = (config) => {
-  let browsers = [];
-
-  if (process.env.TEST_BROWSER_NAME) {
-    browsers = process.env.TEST_BROWSER_NAME.split(',');
-  }
-
-  const my_conf = {
-
-    // base path that will be used to resolve all patterns (eg. files, exclude)
-    basePath: '',
-
-    // frameworks to use
-    // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
-    frameworks: ['mocha'],
-
-    // list of files / patterns to load in the browser
-    files: [
-      // node modules
-      { pattern: 'node_modules/chai/**', included: false },
-      { pattern: 'node_modules/sinon/**', included: false },
-      { pattern: 'node_modules/sinon-chai/**', included: false },
-      // modules to test
-      { pattern: 'app/localization.js', included: false, type: 'module' },
-      { pattern: 'app/webutil.js', included: false, type: 'module' },
-      { pattern: 'core/**/*.js', included: false, type: 'module' },
-      { pattern: 'vendor/pako/**/*.js', included: false, type: 'module' },
-      // tests
-      { pattern: 'tests/test.*.js', type: 'module' },
-      // test support files
-      { pattern: 'tests/fake.*.js', included: false, type: 'module' },
-      { pattern: 'tests/assertions.js', type: 'module' },
-    ],
-
-    client: {
-      mocha: {
-        // replace Karma debug page with mocha display
-        'reporter': 'html',
-        'ui': 'bdd'
-      }
-    },
-
-    // list of files to exclude
-    exclude: [
-    ],
-
-    plugins: [
-      'karma-*',
-      '@chiragrupani/karma-chromium-edge-launcher',
-      { 'launcher:Safari': [ 'type', SafariBrowser ] },
-    ],
-
-    // start these browsers
-    // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
-    browsers: browsers,
-
-    // test results reporter to use
-    // possible values: 'dots', 'progress'
-    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
-    reporters: ['mocha'],
-
-
-    // level of logging
-    // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
-    logLevel: config.LOG_INFO,
-
-
-    // enable / disable watching file and executing tests whenever any file changes
-    autoWatch: false,
-
-    // Continuous Integration mode
-    // if true, Karma captures browsers, runs the tests and exits
-    singleRun: true,
-  };
-
-  config.set(my_conf);
-};
diff --git a/package.json b/package.json
index e28850a8d..111155afa 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,7 @@
   ],
   "scripts": {
     "lint": "eslint app core po/po2js po/xgettext-html tests utils",
-    "test": "karma start karma.conf.js",
+    "test": "web-test-runner",
     "prepublish": "node ./utils/convert.js --clean"
   },
   "repository": {
@@ -46,22 +46,14 @@
     "fs-extra": "latest",
     "globals": "latest",
     "jsdom": "latest",
-    "karma": "latest",
-    "karma-mocha": "latest",
-    "karma-chrome-launcher": "latest",
-    "@chiragrupani/karma-chromium-edge-launcher": "latest",
-    "karma-firefox-launcher": "latest",
-    "karma-ie-launcher": "latest",
-    "karma-mocha-reporter": "latest",
-    "karma-safari-launcher": "latest",
-    "karma-script-launcher": "latest",
     "mocha": "latest",
     "node-getopt": "latest",
     "po2json": "latest",
     "sinon": "latest",
-    "sinon-chai": "latest"
+    "sinon-chai": "latest",
+    "@web/test-runner": "latest",
+    "@web/test-runner-webdriver": "latest"
   },
-  "dependencies": {},
   "keywords": [
     "vnc",
     "rfb",
diff --git a/tests/assertions.js b/tests/assertions.js
index a70122717..34ab038f0 100644
--- a/tests/assertions.js
+++ b/tests/assertions.js
@@ -1,10 +1,6 @@
-import * as chai from '../node_modules/chai/chai.js';
-import sinon from '../node_modules/sinon/pkg/sinon-esm.js';
-import sinonChai from '../node_modules/sinon-chai/lib/sinon-chai.js';
+import * as chai from 'chai';
+import sinonChai from 'sinon-chai';
 
-window.expect = chai.expect;
-
-window.sinon = sinon;
 chai.use(sinonChai);
 
 // noVNC specific assertions
diff --git a/tests/test.base64.js b/tests/test.base64.js
index e5644dcdb..b29a80d86 100644
--- a/tests/test.base64.js
+++ b/tests/test.base64.js
@@ -1,3 +1,5 @@
+import { expect } from 'chai';
+
 import Base64 from '../core/base64.js';
 
 describe('Base64 Tools', function () {
diff --git a/tests/test.browser.js b/tests/test.browser.js
index 692cc23b2..936db2a1a 100644
--- a/tests/test.browser.js
+++ b/tests/test.browser.js
@@ -1,3 +1,5 @@
+import { expect } from 'chai';
+
 import { isMac, isWindows, isIOS, isAndroid, isChromeOS,
          isSafari, isFirefox, isChrome, isChromium, isOpera, isEdge,
          isGecko, isWebKit, isBlink } from '../core/util/browser.js';
diff --git a/tests/test.copyrect.js b/tests/test.copyrect.js
index 60c395287..81e425c62 100644
--- a/tests/test.copyrect.js
+++ b/tests/test.copyrect.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.deflator.js b/tests/test.deflator.js
index b565b9075..181709414 100644
--- a/tests/test.deflator.js
+++ b/tests/test.deflator.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import { inflateInit, inflate } from "../vendor/pako/lib/zlib/inflate.js";
 import ZStream from "../vendor/pako/lib/zlib/zstream.js";
 import Deflator from "../core/deflator.js";
diff --git a/tests/test.display.js b/tests/test.display.js
index d2c51793b..37990e8ee 100644
--- a/tests/test.display.js
+++ b/tests/test.display.js
@@ -1,3 +1,7 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import Base64 from '../core/base64.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.gesturehandler.js b/tests/test.gesturehandler.js
index d2e27ed2a..798eab19e 100644
--- a/tests/test.gesturehandler.js
+++ b/tests/test.gesturehandler.js
@@ -1,3 +1,7 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import EventTargetMixin from '../core/util/eventtarget.js';
 
 import GestureHandler from '../core/input/gesturehandler.js';
diff --git a/tests/test.helper.js b/tests/test.helper.js
index 2c8720c77..17fc568e2 100644
--- a/tests/test.helper.js
+++ b/tests/test.helper.js
@@ -1,3 +1,5 @@
+import { expect } from 'chai';
+
 import keysyms from '../core/input/keysymdef.js';
 import * as KeyboardUtil from "../core/input/util.js";
 
diff --git a/tests/test.hextile.js b/tests/test.hextile.js
index f788fd4dc..70607bef4 100644
--- a/tests/test.hextile.js
+++ b/tests/test.hextile.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.inflator.js b/tests/test.inflator.js
index 11a02f2f4..8553bebaf 100644
--- a/tests/test.inflator.js
+++ b/tests/test.inflator.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import { deflateInit, deflate, Z_FULL_FLUSH } from "../vendor/pako/lib/zlib/deflate.js";
 import ZStream from "../vendor/pako/lib/zlib/zstream.js";
 import Inflator from "../core/inflator.js";
diff --git a/tests/test.int.js b/tests/test.int.js
index 378ebd589..739dde895 100644
--- a/tests/test.int.js
+++ b/tests/test.int.js
@@ -1,3 +1,5 @@
+import { expect } from 'chai';
+
 import { toUnsigned32bit, toSigned32bit } from '../core/util/int.js';
 
 describe('Integer casting', function () {
diff --git a/tests/test.jpeg.js b/tests/test.jpeg.js
index 5cc153f90..692de4488 100644
--- a/tests/test.jpeg.js
+++ b/tests/test.jpeg.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.keyboard.js b/tests/test.keyboard.js
index 11c8b6eb7..0fdacd0c8 100644
--- a/tests/test.keyboard.js
+++ b/tests/test.keyboard.js
@@ -1,3 +1,7 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import Keyboard from '../core/input/keyboard.js';
 
 describe('Key Event Handling', function () {
@@ -591,7 +595,7 @@ describe('Key Event Handling', function () {
             expect(kbd.onkeyevent).to.have.been.calledWith(0xffe1, 'ShiftLeft', true);
             kbd.onkeyevent.resetHistory();
 
-            kbd._handleKeyDown(keyevent('keydown', {code: 'ShiftRight', key: 'Shift', location: 2}));
+            kbd._handleKeyDown(keyevent('keydown', {code: 'ShiftRight', key: 'ShiftFoo', location: 2}));
             expect(kbd.onkeyevent).to.have.been.calledOnce;
             expect(kbd.onkeyevent).to.have.been.calledWith(0xffe2, 'ShiftRight', true);
             kbd.onkeyevent.resetHistory();
diff --git a/tests/test.localization.js b/tests/test.localization.js
index a1cb45474..9678f2d34 100644
--- a/tests/test.localization.js
+++ b/tests/test.localization.js
@@ -1,3 +1,7 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import _, { Localizer, l10n } from '../app/localization.js';
 
 describe('Localization', function () {
diff --git a/tests/test.raw.js b/tests/test.raw.js
index 19b2377f7..aff9384f1 100644
--- a/tests/test.raw.js
+++ b/tests/test.raw.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.rfb.js b/tests/test.rfb.js
index 2be3bfbfc..71129dcd4 100644
--- a/tests/test.rfb.js
+++ b/tests/test.rfb.js
@@ -1,8 +1,13 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import RFB from '../core/rfb.js';
 import Websock from '../core/websock.js';
 import ZStream from "../vendor/pako/lib/zlib/zstream.js";
 import { deflateInit, deflate, Z_DEFAULT_COMPRESSION } from "../vendor/pako/lib/zlib/deflate.js";
 import { encodings } from '../core/encodings.js';
+import { initLogging } from '../core/util/logging.js';
 import { toUnsigned32bit } from '../core/util/int.js';
 import { encodeUTF8 } from '../core/util/strings.js';
 import KeyTable from '../core/input/keysym.js';
@@ -111,6 +116,9 @@ describe('Remote Frame Buffer Protocol Client', function () {
 
         // Avoiding printing the entire Websock buffer on errors
         Websock.prototype.inspect = function () { return "[object Websock]"; };
+
+        // Avoid spamming test output
+        initLogging('none');
     });
 
     after(function () {
diff --git a/tests/test.rre.js b/tests/test.rre.js
index 7b5f73d0e..d16a26e1e 100644
--- a/tests/test.rre.js
+++ b/tests/test.rre.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.tight.js b/tests/test.tight.js
index 3d6b555da..2162dd0f6 100644
--- a/tests/test.tight.js
+++ b/tests/test.tight.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.tightpng.js b/tests/test.tightpng.js
index e7edc8fa6..cac586d62 100644
--- a/tests/test.tightpng.js
+++ b/tests/test.tightpng.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/tests/test.util.js b/tests/test.util.js
index eb7240951..8a48f6a71 100644
--- a/tests/test.util.js
+++ b/tests/test.util.js
@@ -1,4 +1,8 @@
 /* eslint-disable no-console */
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import * as Log from '../core/util/logging.js';
 import { encodeUTF8, decodeUTF8 } from '../core/util/strings.js';
 
@@ -7,11 +11,11 @@ describe('Utils', function () {
 
     describe('logging functions', function () {
         beforeEach(function () {
-            sinon.spy(console, 'log');
-            sinon.spy(console, 'debug');
-            sinon.spy(console, 'warn');
-            sinon.spy(console, 'error');
-            sinon.spy(console, 'info');
+            sinon.stub(console, 'log');
+            sinon.stub(console, 'debug');
+            sinon.stub(console, 'warn');
+            sinon.stub(console, 'error');
+            sinon.stub(console, 'info');
         });
 
         afterEach(function () {
diff --git a/tests/test.websock.js b/tests/test.websock.js
index 53145b360..f13404902 100644
--- a/tests/test.websock.js
+++ b/tests/test.websock.js
@@ -1,3 +1,7 @@
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import Websock from '../core/websock.js';
 import FakeWebSocket from './fake.websocket.js';
 
diff --git a/tests/test.webutil.js b/tests/test.webutil.js
index 9151a0603..4ed087cb6 100644
--- a/tests/test.webutil.js
+++ b/tests/test.webutil.js
@@ -1,6 +1,11 @@
 /* jshint expr: true */
 
+import './assertions.js';
+import { expect } from 'chai';
+import sinon from 'sinon';
+
 import * as WebUtil from '../app/webutil.js';
+import { initLogging } from '../core/util/logging.js';
 
 describe('WebUtil', function () {
     "use strict";
@@ -63,6 +68,9 @@ describe('WebUtil', function () {
             before(function () {
                 chrome = window.chrome;
                 window.chrome = null;
+
+                // Avoid spamming test output
+                initLogging('none');
             });
             after(function () {
                 window.chrome = chrome;
diff --git a/tests/test.zrle.js b/tests/test.zrle.js
index f7c6089d5..a2203b101 100644
--- a/tests/test.zrle.js
+++ b/tests/test.zrle.js
@@ -1,3 +1,6 @@
+import './assertions.js';
+import { expect } from 'chai';
+
 import Websock from '../core/websock.js';
 import Display from '../core/display.js';
 
diff --git a/web-test-runner.config.mjs b/web-test-runner.config.mjs
new file mode 100644
index 000000000..8c312d67d
--- /dev/null
+++ b/web-test-runner.config.mjs
@@ -0,0 +1,78 @@
+import { defaultReporter } from '@web/test-runner';
+import { summaryReporter } from '@web/test-runner';
+import { webdriverLauncher } from '@web/test-runner-webdriver';
+
+let browsers;
+let launchers;
+
+if (process.env.TEST_BROWSER_NAME) {
+    browsers = process.env.TEST_BROWSER_NAME.split(',');
+} else {
+    browsers = ['chrome', 'firefox'];
+    if (process.platform === 'win32') {
+        browsers.push('edge');
+    }
+    if (process.platform === 'darwin') {
+        browsers.push('safari');
+    }
+}
+
+launchers = [];
+
+for (let browser of browsers) {
+    switch (browser) {
+        case 'chrome':
+            launchers.push(webdriverLauncher({
+                capabilities: {
+                    browserName: 'chrome',
+                    'goog:chromeOptions': {
+                        args: ['headless', 'disable-gpu']
+                    },
+                },
+            }));
+            break;
+        case 'firefox':
+            launchers.push(webdriverLauncher({
+                capabilities: {
+                    browserName: 'firefox',
+                    'moz:firefoxOptions': {
+                        args: ['-headless']
+                    }
+                },
+            }));
+            break;
+        case 'edge':
+            launchers.push(webdriverLauncher({
+                capabilities: {
+                    browserName: 'edge',
+                    'ms:edgeOptions': {
+                        args: ['--headless']
+                    }
+                },
+            }));
+            break;
+        case 'safari':
+            launchers.push(webdriverLauncher({
+                capabilities: {
+                    browserName: 'safari',
+                },
+            }));
+            break;
+        default:
+            throw new Error('Unknown browser: ' + browser);
+    }
+}
+
+export default {
+    nodeResolve: true,
+    files: [
+        'tests/test.*.js',
+    ],
+    browsers: launchers,
+    reporters: [
+        defaultReporter(),
+        summaryReporter(),
+    ],
+    // We have small test files, so let's kill hangs quickly
+    testsFinishTimeout: 10000,
+};
\ No newline at end of file