This plugin uses new ServiceWorker and Cache API to allow your users to access the contents of your site while they are offline or under unreliable network situations by caching part of your site.
Once you’ve installed this plugin, anyone visiting your site in browsers that support the Service Workers API will be able of access your content even if they run out of network or experiment network instability.
Configure the plugin in the “Settings > Offline content” section of your WordPress dashboard.