diff --git a/README.md b/README.md
index 19035e3..75b948b 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,12 @@ NEXT - Agar.io Extension
 ## Download
 
 - For Google Chrome: http://snsa.github.io/NEXT/next.chrome.user.js
+- For Mozilla Firefox: http://snsa.github.io/NEXT/next.firefox.user.js
 
 ## Usage
 - Install [Tampermonkey](https://tampermonkey.net/) extension for Google Chrome
-- Install the userscript
+or [Greasemonkey](https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/) for Firefox
+- Install the corresponding userscript you downloaded above for each browser
 - Go to http://agar.io
 
 ## Run in development
diff --git a/deploy.sh b/deploy.sh
index aef95cb..78818d3 100644
--- a/deploy.sh
+++ b/deploy.sh
@@ -14,6 +14,7 @@ cd build
 
 sed -i "s/localhost:8080/snsa.github.io\/NEXT/g" index.html
 cp ../userscripts/next.chrome.user.js .
+cp ../userscripts/next.firefox.user.js .
 
 git init
 git config user.name "SNSA Bot"
diff --git a/userscripts/next.firefox.user.js b/userscripts/next.firefox.user.js
new file mode 100644
index 0000000..ed911ed
--- /dev/null
+++ b/userscripts/next.firefox.user.js
@@ -0,0 +1,43 @@
+// ==UserScript==
+// @name         NEXT
+// @description  The next generation of Agar.io extension
+// @version      0.0.1
+// @author       NEXT
+// @match        http://agar.io/*
+// @match        https://agar.io/*
+// @downloadURL  http://snsa.github.io/NEXT/next.firefox.user.js
+// @updateURL    http://snsa.github.io/NEXT/next.firefox.user.js
+// @grant none
+// ==/UserScript==
+
+function opengradingwindow(htmlContent) {
+  var element = document.createElement('script');
+  var target = document.getElementsByTagName('head')[0] || (document.body || document.documentElement);
+  element.type = 'text/javascript';
+  element.textContent = '(function(html){var d=window.document;d.open();d.write(html);d.close();})(' + JSON.stringify(htmlContent) + ');';
+  target.appendChild(element);
+};
+
+function replacePage(url) {
+  if (!window.PIXI) {
+    var req = new XMLHttpRequest;
+    req.onreadystatechange = function() {
+      if (4 == req.readyState) {
+        if (200 == req.status) {
+          document.documentElement.innerHTML = '<h1>Loading...<h1>';
+          opengradingwindow(req.responseText);
+        }
+      }
+    };
+    req.open('GET', url, true);
+    req.send();
+  }
+}
+var sites = {
+  '/': 'http://snsa.github.io/NEXT/',
+  '/dev': 'http://localhost:8080/'
+};
+var pathname = location.pathname;
+if (sites.hasOwnProperty(pathname)) {
+  replacePage(sites[pathname]);
+};