What is Google Lighthouse?

Google Lighthouse is an open-source, automated tool built by Google for auditing the quality of web pages. It runs a series of tests against a URL and generates a report with scores across four key categories: Performance, Accessibility, Best Practices, and SEO. You can run Lighthouse directly in Chrome DevTools, from the command line, or through automated services like Lightbucket. Each audit produces a score from 0 to 100, giving you a clear snapshot of where your site stands and what needs improvement. Performance measures how fast your page loads and becomes interactive. It looks at metrics like Largest Contentful Paint (LCP), which tracks how long it takes for the main content to appear, and Cumulative Layout Shift (CLS), which measures visual stability as the page loads. A slow LCP or high CLS can frustrate users and hurt your search rankings. Accessibility checks whether your site is usable by people with disabilities. This includes things like proper color contrast, alt text on images, correct heading hierarchy, and keyboard navigation support. A high accessibility score means your site works for more people. Best Practices covers general web development standards. This includes using HTTPS, avoiding deprecated APIs, ensuring images have the correct aspect ratio, and not logging errors to the console. These are baseline hygiene checks that every site should pass. SEO evaluates whether your page follows basic search engine optimization guidelines. It checks for valid meta descriptions, crawlable links, legible font sizes, and proper document structure. While it doesn't replace a full SEO strategy, it catches common mistakes that could prevent your pages from ranking. Lighthouse scores are not static, they can vary between runs due to network conditions, server load, and other factors. This is why running audits regularly and tracking trends over time is more valuable than any single score. Tools like Lightbucket automate this process, letting you schedule recurring reports and monitor how your scores change as you make updates to your site. Whether you are a developer optimizing a new feature, a designer ensuring accessibility, or a marketer tracking SEO health, Lighthouse gives you actionable data to build a better web experience.