Async JavaScript


Eliminate Render-blocking Javascript in above-the-fold content with Async Javascript.

Render-blocking Javascript prevents above-the-fold content on your page from being rendered until the javascript has finished loading. This can impact on your page speed and ultimately your ranking within search engines. It can also impact your users experience.

Async JavaScript gives you full control of which scripts to add a ‘async’ or ‘defer’ attribute to or to exclude to help increase the performance of your WordPress website.


Installation is very straightforward:

  1. Upload the zip-file and unzip it in the /wp-content/plugins/ directory
  2. Activate the plugin through the ‘Plugins’ menu in WordPress
  3. Go to Settings > Async JavaScript menu to load settings page


Installation Instructions

Installation is very straightforward:

  1. Upload the zip-file and unzip it in the /wp-content/plugins/ directory
  2. Activate the plugin through the ‘Plugins’ menu in WordPress
  3. Go to Settings > Async JavaScript menu to load settings page
Which browsers support the ‘async’ and ‘defer’ attributes

The ‘async’ attribute is new in HTML5. It is supported by the following browsers:

  • Chrome
  • IE 10 and higher
  • Firefox 3.6 and higher
  • Safari
  • Opera
Where can I get help?

Async JavaScript is supported via the support forum.

Do you offer professional support/ configuration services?

We offer premium services for Async JavaScript and full web performance optimization services at

What about CSS?

As the name implies, Async JavaScript is built to enhance JavaScript loading only. Async JavaScript does not have any impact on CSS.

We recommend using the awesome Autoptimize plugin alongside Async JavaScript for CSS optimization.

I want out, how should I remove Async JavaScript?
  • Disable the plugin
  • Delete the plugin


Высший класс! PageSpeed 99/99

Спасибо автору! Простая настройка, в админке. Выставил JQuery на async, остальные скрипты на defer и добился результатов PageSpeed 99/99. 1 бал потерял из-за счетчиков Метрики, да и фиг с ним. Плагин высший пилотаж!

Loved it!

First we tested this plugin on our site which deals with water tank cleaning service , initial results were good.

But pagespeed insight results didn’t changed much,

Then tested with W3Total Cache, LiteSpeed plugin, it worked like charm.

Pagespeed has improved a lot compared to previous results, though we’re still working on optimizing it further.

Read all 34 reviews

Contributors & Developers

“Async JavaScript” is open source software. The following people have contributed to this plugin.


Translate “Async JavaScript” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.


  • bugfix: only load asyncjs’ JS & CSS on own settings page as reported by Marat Petrov
  • bugfix: check if jQuery chosen is correctly loaded before using it (based on same report, thanks Marat!)
  • update jQuery Chosen lib
  • small readme tweaks

  • ASync JS is now maintained by Frank Goossens (Optimizing Matters), thanks for the great job done David!
  • Moved all Pro features into the standard version.
  • Some code refactoring
  • Made strings ready for translations

  • MOD: Added User Agent to GTMetrix requests

  • MOD: Check for GTMetrix class existance prior to including class

  • FIX: Issue converting array for plugin & theme exclusions

  • FIX: Sanitise all $_GET and all $_POST
  • FIX: Add nonce to ajax calls

  • MOD: Dashboard Widget and Notices only available to Administrators

  • NEW: Added quick settings buttons to allow common settings to be quickly applied
  • NEW: Added current version info to help page

  • FIX: Some installs not saving plugin / theme exclusions due to theme incompatibility

  • MOD/FIX: On some WordPress installs is_plugin_active function being called too early. Moved is_plugin_active into dedicated function called via admin_init as per codex:

  • FIX: Incorrect textarea identifier preventing exclusion save

  • FIX: Resolve early loading of plugin causing fatal error due to function not available yet
  • FIX: CSS / JS not loading

  • MOD: Add text to advise running Wizard is not mandatory

  • massive Massive MASSIVE rewrite of Async JavaScript!!!
  • Now includes a setup Wizard, Status page, Settings page and a help page.
  • Communicates directly with GTmetrix (account required)
  • Automaticall transfers existing settings from Async JavaScript to Async JavaScript