diff --git a/package.json b/package.json
index 7762a67..a8b59f9 100644
--- a/package.json
+++ b/package.json
@@ -7,6 +7,7 @@
   },
   "dependencies": {
     "deep-diff": "^0.3.3",
+    "firebase": "^2.3.2",
     "lesshat": "^3.0.2",
     "lodash": "^3.10.1",
     "marked": "^0.3.5",
diff --git a/src/js/components/Header.jsx b/src/js/components/Header.jsx
index 20d1ec9..4bf3a04 100644
--- a/src/js/components/Header.jsx
+++ b/src/js/components/Header.jsx
@@ -27,7 +27,7 @@ export default React.createClass({
 
     // Sign-in/out.
     let user;
-    if (props.user.uid) {
+    if (props.user && 'uid' in props.user) {
       user = (
         <div className="right">
           <a onClick={this._onSignOut}>
diff --git a/src/js/models/config.js b/src/js/models/config.js
new file mode 100644
index 0000000..ce5e729
--- /dev/null
+++ b/src/js/models/config.js
@@ -0,0 +1,33 @@
+export default {
+  // Firebase app name.
+  "firebase": "burnchart",
+  // Data source provider.
+  "provider": "github",
+  // Fields to keep from GH responses.
+  "fields": {
+    "milestone": [
+      "closed_issues",
+      "created_at",
+      "description",
+      "due_on",
+      "number",
+      "open_issues",
+      "title",
+      "updated_at"
+    ]
+  },
+  // Chart configuration.
+  "chart": {
+    // Days we are not working. Mon = 1
+    "off_days": [ ],
+    // How does a size label look like?
+    "size_label": /^size (\d+)$/,
+    // Process all issues as one size (ONE_SIZE) or use labels (LABELS).
+    "points": 'ONE_SIZE'
+  },
+  // Request pertaining.
+  "request": {
+    // Default timeout of 5s.
+    "timeout": 5e3
+  }
+};
diff --git a/src/js/stores/appStore.js b/src/js/stores/appStore.js
index 6599dc3..91cd926 100644
--- a/src/js/stores/appStore.js
+++ b/src/js/stores/appStore.js
@@ -1,9 +1,15 @@
 import _ from 'lodash';
+import Firebase from 'firebase';
 
 import Store from '../core/Store.js';
 
 import actions from '../actions/appActions.js';
 
+import config from '../models/config.js';
+
+// Setup a new client.
+let client;
+
 class AppStore extends Store {
 
   // Initial payload.
@@ -15,7 +21,7 @@ class AppStore extends Store {
       user: {}
     });
 
-    // Listen to all app actions
+    // Listen to all app actions.
     actions.onAny((obj, event) => {
       let fn = ('on.' + event).replace(/[.]+(\w|$)/g, (m, p) => {
         return p.toUpperCase();
@@ -23,14 +29,38 @@ class AppStore extends Store {
 
       (fn in this) && this[fn](obj);
     });
+
+    client = new Firebase("https://" + config.firebase + ".firebaseio.com");
+
+    // When user is already authenticated.
+    client.onAuth((data={}) => actions.emit('firebase.auth', data));
   }
 
   onUserSignin() {
-    console.log('in');
+    client.authWithOAuthPopup("github", function(err, data) {
+      if (!err) return actions.emit('firebase.auth', data);
+
+      actions.emit('notify', {
+        'text': err.toString(),
+        'type': 'alert',
+        'system': true          
+      });
+    }, {
+      'rememberMe': true,
+      // See https://developer.github.com/v3/oauth/#scopes
+      'scope': 'repo'
+    });
   }
 
-  onUserSignOut() {
-    console.log('out');
+  // Sign-out a user.
+  onUserSignout() {
+    this.set('user', {});
+    client.unauth();
+  }
+
+  // Called by Firebase.
+  onFirebaseAuth(data) {
+    this.set('user', data);
   }
 
 }