The Zinn® Cache plugin

Zinn® Cache is a free caching plugin for WordPress. On a site we host it drives the LiteSpeed page cache your server already runs, telling it what to cache and when to throw it away. Where nginx, Varnish or Apache already caches pages in front of WordPress, it purges that cache instead of adding a second one. On any other server it keeps each page as a file and serves it before WordPress loads, so it works wherever your site is hosted.

It is free and listed in the WordPress.org plugin directory: wordpress.org/plugins/zinn-cache. On a site we host it is installed for you; if it has been removed, reinstall it from Plugins → Add New Plugin by searching for Zinn® Cache.

Check this first

Zinn Digital® → Cache → Status says which page cache is in use — the LiteSpeed server's, an nginx, Varnish or Apache cache in front of the site, or the plugin's own file cache — and whether the Redis object cache is really storing data. Check now requests your newest pages as a visitor would and shows how often each cache answered. On a site we host it should say LiteSpeed; if it does not, open a ticket and we will look at the server, not at your site.

Purging, and why you rarely need to

Publishing a post or editing a page already purges what changed. The plugin purges by tag, so editing one post clears that post, the pages it appears on and your feeds — not your whole site. A change that touches every page (an update, a plugin activation, a menu or a theme) starts a paced refresh: every page is refreshed a batch a minute, newest first, instead of the whole cache being emptied at once, so the site stays fast while it happens.

To clear one page, type its address on the Status tab and press Purge these addresses. Empty all now is on the same screen for the rare times you want everything gone at once, such as after editing a template file over SFTP.

The Redis object cache

The toggle installs a drop-in that keeps WordPress's own internal lookups in memory between requests. It helps most on:

• WooCommerce and any shop with a large catalogue
• sites with many plugins
• membership or forum sites, where almost every page is logged-in

It helps least on a small brochure site that is already fully page-cached. Switch it on, watch the site for a day, and switch it off again if you see nothing — it is reversible and it never overwrites a drop-in another plugin installed.

Exclusions

Cart, checkout, my-account and any logged-in session are never cached, and you do not have to configure that. Add your own rules only when you have a page that must always be fresh — each rule you add is a page that stops being fast, so add them one at a time.

If a change is not showing

In this order: purge that page from the plugin screen; hard-reload in your browser (Ctrl-Shift-R); check whether a CDN in front of us is holding it. Three different caches can hold a page and only the first one is ours.