Autoptimize

by Optimizing Matters
Tested with WP 7.1.3 Free, GPLv2

Our take

Autoptimize is the classic free tool for making a theme's CSS and JavaScript lighter, and it improves PageSpeed scores on many sites. It is not a page cache, so combine it with one, and test your site after enabling JavaScript options, because aggressive settings can break sliders or menus. Turn options on one at a time.

Good

  • Minifies and defers CSS and JavaScript
  • Lazy loading and Google Fonts optimization
  • Works alongside any page cache plugin
  • Very flexible for developers

Watch out

  • Not a page cache on its own
  • Aggressive settings can break some themes
  • Critical CSS has to be added by hand in the free version

Autoptimize targets one of the main reasons themes feel slow: too many CSS and JavaScript files loading before the page can appear. It can shrink those files, merge them, move scripts out of the way and keep the browser from waiting on anything that isn’t needed for the first view.

What Autoptimize optimizes

  • CSS: minify, combine, inline critical CSS and load the rest later
  • JavaScript: minify, combine or defer so it doesn’t block rendering
  • HTML: remove unneeded whitespace and comments
  • Images: lazy loading, plus optional optimization with WebP and AVIF
  • Extras: Google Fonts optimization and removal of WordPress emoji scripts

How to set it up safely

Enable one group of options at a time and check your site after each step, ideally in a private window. If something breaks, the plugin lets you exclude individual files. Autoptimize Pro adds page caching, image optimization through a CDN and automatic critical CSS.