Speed Kit

Speed Kit adds a synchronized cache layer to WordPress request handling. It is supported for sites using Plesk with the Plesk Speed Kit extension. You also need an existing Speed Kit license; new subscriptions through WordPress are unavailable.

Check requirements and activate

The website must use SSL because Service Workers require a secure connection. The plugin needs permission to write its Service Worker file to the website root at /speed-kit-sw.js.

1. In WordPress, open Plugins and pick Add New.
2. Search for Speed Kit, install the plugin and activate it.
3. Follow the plugin setup, which adds the Service Worker.

The plugin listing warns that Speed Kit has not been tested with the latest three major WordPress releases and may have compatibility issues.

How requests reach the cache

After activation, the Service Worker routes requests from the WordPress backend through a cache synchronized with the site. Speed Kit works alongside existing systems, CDNs and load balancers, distributes content to edge locations and uses the user’s browser cache. Its caching is designed for static documents and dynamic content such as HTML, search results, comments and personalization. The service also handles network protocols and tailored images.

Settings let you use allowlists and blocklists to choose which pages and resources Speed Kit handles, control cache updates and revalidate the site. Automatic picture optimization is also available. WooCommerce integration is included. Caching is inactive for logged-in users, when a WooCommerce cart or wishlist contains entries, and after repeated cache update failures.

Trial, continuation and measurement

The plugin description states that the first 10 days are free and require no bank details, followed by a continuation price of 9.99 € per month. If you take no action after the trial, Speed Kit stops handling requests and the backend handles them again; the site remains online during the transition.

Speed Kit is intended for sites where page delivery affects user experience, search visibility, time on site or e-commerce funnel performance. The service description reports about 7,000 websites, 200 million users monthly, 3.6 billion euros of annual revenue accelerated and capacity for 25,000 requests per second.

To assess performance, test the site after installation with Page Speed Analyzer or WebPageTest. The plugin description notes that most other popular performance tools may not provide accurate results for sites using Service Workers.