Danila Vershinin

Cacheability makes your WordPress site a better HTTP citizen, improving SEO and cache efficiency.
<h4>Free Features</h4>
Soft 404 Fix
WordPress returns HTTP 200 for empty search results, invalid tag pages, and empty category archives. Google marks these as “soft 404” errors in Search Console, hurting your SEO.
Cacheability fixes this by returning proper 404 status codes when:
<ul>
<li>Search results are empty (<code>/?s=nonexistent</code>)</li>
<li>Tag archives are empty (<code>/tag/nonexistent/</code>)</li>
<li>Category archives are empty</li>
<li>Author archives are empty</li>
</ul>
Smart Cache-Control Headers
Automatically adds <code>s-maxage</code> headers so Varnish, NGINX, and CDNs can cache your pages efficiently without affecting browser caching behavior.
<ul>
<li>Search/404 pages: 1 hour cache</li>
<li>All other pages: 1 year cache (your purge plugin handles invalidation)</li>
</ul>
<h4>Cacheability Pro</h4>
Upgrade to <a href="https://www.getpagespeed.com/web-apps/cacheability-pro" rel="nofollow ugc">Cacheability Pro</a> for advanced features:
<ul>
<li>Cache Warming — Automatically warm pages after purging so visitors never hit cold cache</li>
<li>Conditional GET (304) — Return 304 Not Modified for unchanged content, saving bandwidth</li>
<li>ESI Support — Cache pages with dynamic nonces (comments, login forms)</li>
<li>Rate-Limit Safe — Smart request queuing to avoid 429 errors</li>
<li>Sitemap Warming — Warm all pages from sitemap after full purge</li>
<li>WP-CLI Commands — <code>wp cacheability warm</code> and more</li>
<li>Priority Support — Get help when you need it</li>
</ul>
<a href="https://www.getpagespeed.com/web-apps/cacheability-pro" rel="nofollow ugc">Get Cacheability Pro →</a>

Cacheability

HTTP optimization for WordPress. Fixes soft 404 errors and adds smart cache headers.

Razvan Stanga

Complete WordPress Varnish Cache 3.x/4.x/5.x and Nginx Proxy Cache integration.
This plugin handles all integration with Varnish Cache and Nginx Proxy Cache. It was designed for high traffic websites.
Main features
<ul>
<li>admin interface, see screenshots</li>
<li>console for manual purges, supports regular expressions so you can purge an entire folder or just a single file</li>
<li>supports every type of Varnish Cache implementation, see screenshots for examples</li>
<li>unlimited number of Varnish Cache servers</li>
<li>use of custom headers when communicating with Varnish Cache does not interfere with other caching plugins, cloudflare, etc</li>
<li>Varnish Cache configuration generator</li>
<li>purge key method so you don’t need to setup ACLs</li>
<li>debugging</li>
<li>actively maintained</li>
</ul>
You can control the following from the Varnish Caching admin panel :
<ul>
<li>Enable/Disable caching</li>
<li>Homepage cache TTL</li>
<li>Cache TTL (for every other page)</li>
<li>IPs/Hosts to clear cache to support every type of Varnish Cache implementation</li>
<li>Override default TTL in posts/pages</li>
<li>Purge key based PURGE</li>
<li>Logged in cookie</li>
<li>Debugging option</li>
<li>console for precise manual purges</li>
</ul>
This plugin also auto purges Varnish Cache / Nginx Proxy Cache when your site is modified.
Varnish Caching sends a PURGE request to Varnish Cache / Nginx Proxy Cache when a page or post is modified. This occurs when editing, publishing, commenting or deleting an item, and when changing themes. 
Not all pages are purged every time, depending on your Varnish / Nginx Proxy Cache configuration. When a post, page, or custom post type is edited, or a new comment is added, only the following pages will purge:
<ul>
<li>The front page</li>
<li>The post/page edited</li>
<li>Any categories or tags associated with the page</li>
</ul>
<a href="https://www.varnish-cache.org/" rel="nofollow ugc">Varnish Cache</a> / <a href="https://www.nginx.com/blog/nginx-caching-guide/" rel="nofollow ugc">Nginx Proxy Cache</a> is a web application accelerator also known as a caching HTTP reverse proxy. You install it in front of any server that speaks HTTP and configure it to cache the contents. This plugin does not install Varnish/Nginx for you, nor does it configure Varnish/Nginx for WordPress. It’s expected you already did that on your own using the provided config files.
Inspired from the following :
<ul>
<li>https://wordpress.org/plugins/varnish-http-purge/</li>
<li>https://github.com/dreamhost/varnish-vcl-collection/</li>
</ul>

Varnish/Nginx Proxy Caching

Wordpress Varnish Cache 3.x/4.x/5.x and Nginx Proxy Cache integration

Cacheability vs Varnish/Nginx Proxy Caching