Site Kit by Google is Google's official plugin for WordPress, the open-source content management system that many websites run on. It connects a WordPress site to Google's services for site owners and shows their data in one dashboard inside the WordPress admin area, without code editing.
The site owner installs it from the WordPress plugin screen, signs in with a Google account and verifies the site. Site Kit then places the needed code on the site and connects modules: Search Console (traffic and performance in Google Search), Google Analytics (how visitors find and use the site), PageSpeed Insights (speed analysis and suggestions), AdSense, Google Ads, Tag Manager (manages tracking tags without code changes), Sign in with Google and Reader Revenue Manager (subscriptions, contributions and paywalls). Metrics are shown for the whole site and for each single page, from the WordPress admin bar. It needs WordPress 5.2 and PHP 7.4 or newer.
Site Kit is free and open source under the Apache 2.0 license, with its code on GitHub.