googlechrome/lighthouse

Lighthouse is an automated tool that analyzes web pages and produces a scored report covering performance, accessibility, best practices, and SEO (search engine optimization). Think of it as a health check for a website: you point it at a URL, it loads the page in a controlled environment, measures how fast it loads and how well it is built, and then gives you a score from 0 to 100 in each category along with specific recommendations for improvement. It works by launching a browser in the background, loading the page, collecting data (how long key content takes to appear, whether images have descriptive labels for screen readers, whether the page is secure, and so on), and then running those measurements through a set of audits, checks against defined best practices. The results are saved as an HTML report you can open in a browser, or as JSON for automated pipelines. You can run Lighthouse in several ways: directly from the Lighthouse tab in Chrome's built-in developer tools, as a browser extension, or as a command-line tool for automated or repeated testing. The command-line version is useful for running audits as part of a build process so that performance regressions are caught before a site goes live. It can also be imported as a module into your own JavaScript code. You would use it whenever you want objective measurements of a web page's quality and a prioritized list of specific things to fix. The tech stack is JavaScript, running on Node.