Easy Critical CSS

Easy Critical CSS is a lightweight WordPress plugin that allows you to add Critical CSS to any page on your site, improving your site’s loading speed and performance.

Features:
– Easily add Critical CSS and Secondary CSS to any page
– Secondary CSS removes all unused CSS rules and stylesheets, ensuring only a single optimized CSS file loads
– Supports posts, pages, archives, and taxonomy pages
– Fully compatible with caching plugins (WP Rocket, W3 Total Cache, WP Super Cache, etc.)
– Customizable settings for individual pages
– Stores Critical CSS in your choice of the database or as static files
– Optional API service (API key required) for automated Critical & Secondary CSS generation through CriticalCSS.net
– Background processing to for smooth, non-blocking performance

Why Use Critical CSS?

Critical CSS ensures above-the-fold content loads first by reducing render-blocking styles. This helps you boost Core Web Vitals, improve page speed scores, and deliver a better experience to your visitors.

Want to try it out first? You can generate free one-off Critical CSS at CriticalCSS.net and manually apply it to your site using the plugin settings.

External services

This plugin interacts with external third-party services in order to provide its functionality. Below is a detailed breakdown of these interactions:

1. Critical CSS API (api.criticalcss.net)
   This service generates critical and secondary CSS used to optimize your site’s CSS delivery and improve page load times.

   • Data Sent: The URL, CSS generation preferences, generation status, and HTML content of pages from your website.
   • When: Data is transmitted only if you have explicitly enabled the Auto generation mode, and occurs whenever Critical CSS or Secondary CSS needs to be generated or regenerated.
   • Links: Terms of Service, Privacy Policy.

2. Cloudflare API (api.cloudflare.com)
   This service is used to automatically clear your Cloudflare cache after new critical CSS is generated, ensuring your visitors see updated styles immediately.

   • Data Sent: Authentication credentials (Cloudflare email, API key, and zone ID) and instructions for purging the cache.
   • When: Data is sent only if CLOUDFLARE_EMAIL, CLOUDFLARE_API_KEY, and CLOUDFLARE_ZONE_ID are defined in your site’s configuration.
   • Links: Terms of Service, Privacy Policy.

3. Kinsta Cache Clear (localhost)
   If your site is hosted on Kinsta, this plugin can trigger a cache clear after generating new critical CSS, ensuring immediate availability of updated styles.

   • Data Sent: A cache-clear request to your site’s local server endpoint provided by Kinsta. No sensitive or identifying information is transmitted beyond the local environment.
   • When: Data is sent only when your site detects that it’s running on Kinsta infrastructure (KINSTA_CACHE_ZONE environment variable is present).
   • Links: Kinsta Terms of Service, Kinsta Privacy Policy.

4. Freemius API (api.freemius.com and wp.freemius.com)
   Used to manage licensing, validate API keys, and handle plugin updates and account management.

   • Data Sent: Freemius sends and receives licensing information and plugin activation status, including your site’s URL, plugin version, API key, and licensing details.
   • When: Data is transmitted only after explicitly opting in through the plugin’s settings page or upon activation of a purchased API key. By default, the plugin does not send any data to Freemius.
   • Links: Freemius Terms of Service, Freemius Privacy Policy.