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WP Critical CSS

Self-hosted critical CSS, generated by a real browser - not a WP Rocket subscription. No metered quota, no SaaS: your own container, your own control.

WP Rocket's "Remove Unused CSS" and QUIC.cloud's free tier solve one problem - shipping only the CSS a page needs above the fold - behind a paid plan or a quota. WP Critical CSS does the same job with two parts you run yourself:

• a small service (a Node container with headless Chrome) that renders each page and extracts the above-the-fold CSS for mobile and desktop separately, and
• a WordPress plugin that stores that CSS, inlines it into the page and defers the page's regular stylesheets.

No account, no per-page limits, and no third-party service ever sees your site's HTML.

How it fits together

flowchart LR
    P["Post saved or published"] --> Q
    S["Daily sitemap sweep (cron)"] --> Q["Generation queue"]
    Q --> R["Headless Chrome: mobile + desktop"]
    R -- "POST /wp-json/wpcc/v1/critical-css" --> W["WordPress"]
    W -- "inline + defer" --> V(("Visitor"))

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Two independent triggers feed one queue: saving a post regenerates just that page shortly after (through WP-Cron), and a daily sweep of your sitemap catches everything else. The details are on How It Works.

Where to start

I want to...	Read
Set it up for the first time	Getting Started
Look up a setting, a default or an endpoint	Configuration
Install or verify the WordPress plugin	Install the Plugin
Understand what happens to a page	How It Works
Know what is protected and what I must do	Security Overview
Lock the container's network down further	Network Egress Filtering
Fix something that does not work	Troubleshooting
Update to a new release, or roll back	Upgrading and Releases
Change these pages	Editing the Wiki

Good to know

• Not on WordPress.org. The plugin is installed from a GitHub release zip.
• Only the latest release is supported. Deploy from a tagged release, not from main.
• Nothing breaks if it stops. Pages without generated CSS load their stylesheets exactly as before the plugin existed; see Upgrading and Releases.
• Deeper reading lives in the repository: architecture, security controls, the changelog, and the vulnerability reporting policy.