diff --git a/config.json.example b/config.json.example
index 793dcc1f14..3b79e77aab 100644
--- a/config.json.example
+++ b/config.json.example
@@ -69,5 +69,9 @@
           "KEY": "key.pem",
           "CERT": "cert.pem"
         }
+    },
+    "FIREBASE": {
+        "APP": "app-name",
+        "SECRET": "secret"
     }
 }
diff --git a/package.json b/package.json
index 20bb60b471..454a46e4d4 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
     "domain-middleware": "~0.1.0",
     "express": "~3.17.5",
     "express-csv": "~0.6.0",
+    "firebase": "^2.2.9",
     "grunt": "~0.4.1",
     "grunt-browserify": "^3.3.0",
     "grunt-cli": "~0.1.9",
diff --git a/website/src/models/group.js b/website/src/models/group.js
index 2ddbcf5d92..36699bf356 100644
--- a/website/src/models/group.js
+++ b/website/src/models/group.js
@@ -6,6 +6,8 @@ var async = require('async');
 var logging = require('../logging');
 var Challenge = require('./../models/challenge').model;
 
+// NOTE any change to groups' members in MongoDB will have to be run through the API
+// changes made directly to the db will cause Firebase to get out of sync
 var GroupSchema = new Schema({
   _id: {type: String, 'default': shared.uuid},
   name: String,