diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 00000000..20fd7a19
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,3 @@
+[*.js]
+indent_style=space
+indent_size=4
diff --git a/.gitignore b/.gitignore
index d48db0e7..e9ba91e2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,3 +41,6 @@ nosetests.xml
 .pydevproject
 
 .vagrant
+
+# Node
+node_modules/
diff --git a/.travis.yml b/.travis.yml
index 77b52ef5..559895df 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,11 @@ python:
 
 os:
   - linux
-#  - osx
+
+cache:
+  directories:
+    - $HOME/.cache/pip
+    - node_modules
 
 sudo: false
 
@@ -16,9 +20,11 @@ install:
   - pip install git+https://github.com/esnme/ultrajson.git
   - python setup.py -q install
   - pip install coverage pytest-cov coveralls --use-mirrors
+  - npm install
 
 script:
-    python setup.py test
+  - python setup.py test
+  - cd karma-tests && make test
 
 after_success:
     coveralls
diff --git a/karma-tests/Makefile b/karma-tests/Makefile
new file mode 100644
index 00000000..bb80eeec
--- /dev/null
+++ b/karma-tests/Makefile
@@ -0,0 +1,4 @@
+NODE_BIN_DIR=../node_modules/.bin
+
+test:
+	$(NODE_BIN_DIR)/karma start --single-run
diff --git a/karma-tests/karma.conf.js b/karma-tests/karma.conf.js
new file mode 100644
index 00000000..b40190f2
--- /dev/null
+++ b/karma-tests/karma.conf.js
@@ -0,0 +1,90 @@
+if (!process.env['SAUCE_USERNAME'] || !process.env['SAUCE_ACCESS_KEY']) {
+    console.error('Sauce Labs account details not set, skipping Karma tests');
+    process.exit(0);
+}
+
+var sauceLabsConfig = {
+    testName: 'PyWB Client Tests',
+};
+
+// see https://github.com/karma-runner/karma-sauce-launcher/issues/73
+if (process.env.TRAVIS_JOB_NUMBER) {
+    sauceLabsConfig.startConnect = false;
+    sauceLabsConfig.tunnelIdentifier = process.env.TRAVIS_JOB_NUMBER;
+}
+
+var WOMBAT_JS_PATH = 'pywb/static/wombat.js';
+
+var customLaunchers = {
+    sl_chrome: {
+        base: 'SauceLabs',
+        browserName: 'chrome',
+    },
+
+    sl_firefox: {
+        base: 'SauceLabs',
+        browserName: 'firefox',
+    },
+
+/*  Safari and Edge are currently broken in
+    pywb.
+
+    See: https://github.com/ikreymer/pywb/issues/148 (Edge)
+         https://github.com/ikreymer/pywb/issues/147 (Safari)
+
+    sl_safari: {
+        base: 'SauceLabs',
+        browserName: 'safari',
+        platform: 'OS X 10.11',
+        version: '9.0',
+    },
+    sl_edge: {
+        base: 'SauceLabs',
+        browserName: 'MicrosoftEdge',
+    },
+*/
+};
+
+module.exports = function(config) {
+  config.set({
+    basePath: '../',
+
+    frameworks: ['mocha', 'chai'],
+
+    files: [
+      {
+        pattern: WOMBAT_JS_PATH,
+        watched: true,
+        included: false,
+        served: true,
+      },
+      'karma-tests/*.spec.js',
+    ],
+
+    preprocessors: {},
+
+    reporters: ['progress'],
+
+    port: 9876,
+
+    colors: true,
+
+    logLevel: config.LOG_INFO,
+
+    autoWatch: true,
+
+    sauceLabs: sauceLabsConfig,
+
+    // use an extended timeout for capturing Sauce Labs
+    // browsers in case the service is busy
+    captureTimeout: 3 * 60000,
+
+    customLaunchers: customLaunchers,
+
+    browsers: Object.keys(customLaunchers),
+
+    singleRun: false,
+
+    concurrency: Infinity
+  })
+};
diff --git a/karma-tests/wombat.spec.js b/karma-tests/wombat.spec.js
new file mode 100644
index 00000000..7012da83
--- /dev/null
+++ b/karma-tests/wombat.spec.js
@@ -0,0 +1,148 @@
+var WOMBAT_SRC = '../pywb/static/wombat.js';
+var DEFAULT_TIMEOUT = 20000;
+
+// creates a new document in an <iframe> and runs
+// a WombatJS test case in it.
+//
+// A new <iframe> is used for each test so that each
+// case is run with fresh Document and Window objects,
+// since Wombat monkey-patches many Document and Window
+// functions
+//
+function runWombatTest(testCase, done) {
+    // create an <iframe>
+    var testFrame = document.createElement('iframe');
+    testFrame.src = '/dummy.html';
+    document.body.appendChild(testFrame);
+
+    testFrame.contentWindow.addEventListener('load', function () {
+        var testDocument = testFrame.contentDocument;
+
+        function runFunctionInIFrame(func) {
+            testFrame.contentWindow.eval('(' + func.toString() + ')()');
+        }
+
+        // expose an error reporting function to the <iframe>
+        window.reportError = function(ex) {
+            done(new Error(ex));
+        };
+
+        // expose chai assertions to the <iframe>
+        window.assert = assert;
+
+        runFunctionInIFrame(function () {
+            // re-assign the iframe's console object to the parent window's
+            // console so that messages are intercepted by Karma
+            // and output to wherever it is configured to send
+            // console logs (typically stdout)
+            console = window.parent.console;
+            window.onerror = function (message, url, line, col, error) {
+                if (error) {
+                    console.log(error.stack);
+                }
+                reportError(new Error(message));
+            };
+
+            // expose chai's assertion testing API to the test script
+            assert = window.parent.assert;
+            reportError = window.parent.reportError;
+        });
+
+        try {
+            runFunctionInIFrame(testCase.initScript);
+        } catch (e) {
+            throw new Error('Configuring Wombat failed: ' + e.toString());
+        }
+
+        try {
+            testFrame.contentWindow.eval(testCase.wombatScript);
+            runFunctionInIFrame(function () {
+                new window._WBWombat(wbinfo);
+            });
+        } catch (e) {
+            throw new Error('Initializing WombatJS failed: ' + e.toString());
+        }
+
+        if (testCase.html) {
+            testDocument.body.innerHTML = testCase.html;
+        }
+
+        if (testCase.testScript) {
+            try {
+                runFunctionInIFrame(testCase.testScript);
+            } catch (e) {
+                throw new Error('Test script failed: ' + e.toString());
+            }
+        }
+
+        testFrame.remove();
+        done();
+    });
+}
+
+describe('WombatJS', function () {
+    this.timeout(DEFAULT_TIMEOUT);
+
+    var wombatScript;
+
+    before(function (done) {
+        // load the source of the WombatJS content
+        // rewriting script
+        var req = new XMLHttpRequest();
+        req.open('GET', '/base/pywb/static/wombat.js');
+        req.onload = function () {
+            wombatScript = req.responseText;
+            done();
+        };
+        req.send();
+    });
+
+    it('should load', function (done) {
+        runWombatTest({
+            initScript: function () {
+                wbinfo = {
+                    wombat_opts: {},
+                };
+            },
+            wombatScript: wombatScript,
+        }, done);
+    });
+
+    it('should rewrite document.baseURI', function (done) {
+        runWombatTest({
+            initScript: function () {
+                wbinfo = {
+                    wombat_opts: {},
+                    prefix: window.location.origin,
+                    wombat_ts: '',
+                };
+            },
+            wombatScript: wombatScript,
+            testScript: function () {
+                var baseURI = document.baseURI;
+                if (typeof baseURI !== 'string') {
+                    throw new Error('baseURI is not a string');
+                }
+                assert.equal(baseURI, 'http:///dummy.html');
+            },
+        }, done);
+    });
+
+    it('should rewrite links in dynamically injected <a> tags', function (done) {
+        runWombatTest({
+            initScript: function () {
+                wbinfo = {
+                    wombat_opts: {},
+                    prefix: window.location.origin,
+                    wombat_ts: '',
+                };
+            },
+            wombatScript: wombatScript,
+            html: '<a href="foobar.html" id="link">A link</a>',
+            testScript: function () {
+                var link = document.getElementById('link');
+                assert.equal(link.href, 'http:///foobar.html');
+            },
+        }, done);
+    });
+});
diff --git a/package.json b/package.json
new file mode 100644
index 00000000..241a71ba
--- /dev/null
+++ b/package.json
@@ -0,0 +1,34 @@
+{
+  "name": "pywb",
+  "version": "1.0.0",
+  "description": "Web archival replay tools",
+  "main": "index.js",
+  "directories": {
+    "doc": "doc",
+    "test": "tests"
+  },
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/ikreymer/pywb.git"
+  },
+  "author": "",
+  "license": "GPL-3.0",
+  "bugs": {
+    "url": "https://github.com/ikreymer/pywb/issues"
+  },
+  "homepage": "https://github.com/ikreymer/pywb#readme",
+  "devDependencies": {
+    "chai": "^3.4.1",
+    "karma": "^0.13.15",
+    "karma-chai": "^0.1.0",
+    "karma-chrome-launcher": "^0.2.1",
+    "karma-firefox-launcher": "^0.1.7",
+    "karma-html2js-preprocessor": "^0.1.0",
+    "karma-mocha": "^0.2.1",
+    "karma-sauce-launcher": "^0.3.0",
+    "mocha": "^2.3.4"
+  }
+}