Speed Kit adds a Service Worker and synchronized cache to WordPress

Speed Kit routes WordPress requests through a cache synchronized with the site. The plugin is supported for Plesk hosting used with the Plesk Speed Kit extension. Existing Speed Kit license holders can continue using it, but new subscriptions through WordPress are unavailable.

How requests and caching work

After activation, Speed Kit includes a Service Worker at /speed-kit-sw.js. It routes requests from the WordPress backend to the synchronized cache, delivering content from the user side without changes to backend servers or DNS settings. Speed Kit uses a CDN and the visitor’s browser cache, and distributes synchronized content to edge locations. Compared with a CDN cache alone, it also uses the browser cache and is designed to handle dynamic content such as search, comments and personalization alongside static documents.

Settings let you control which pages and resources Speed Kit handles, how often cached content is updated, and which URLs are included or excluded. The plugin also provides settings for automatic picture optimization. Its WooCommerce integration is included. Caching is inactive for logged-in visitors, for WooCommerce sessions with items in the cart or wishlist, and after repeated cache update failures.

Requirements and compatibility

Use requires Plesk with the Plesk Speed Kit extension and an existing Speed Kit license. The website must use SSL, and the plugin needs write access to the WordPress root directory to place the Service Worker. The plugin listing warns that Speed Kit has not been tested with the latest three major WordPress releases and may no longer be maintained or supported; compatibility issues may occur.

Listed trial terms and performance checks

The listing describes a free first 10-day trial with no bank details required, followed by continued use at 9.99 € per month. It also states that new subscriptions through WordPress are unavailable. If no action is taken after the trial, Speed Kit stops handling requests and the backend handles them again; the site remains online.

To assess performance, the listing recommends its Page Speed Analyzer or WebPageTest. It notes that many other popular performance tools may not accurately test sites using Service Workers. The listing reports about 7,000 sites, 200 million monthly users, 3.6 billion euros of annual revenue accelerated, and a scale of 25,000 requests per second.