Google Lighthouse

Google Lighthouse is an open-source tool developed by Google for performing technical audits of websites. It evaluates aspects such as Performance, Accessibility, Best Practices, SEO, and Progressive Web App (PWA) capabilities. Lighthouse helps identify areas for improvement to enhance user experience and search engine visibility.

Google Lighthouse can be accessed through several methods:

PageSpeed Insights: Provides a performance and SEO report based on Lighthouse audits.

Chrome DevTools: Integrated within the Chrome browser’s developer tools for real-time analysis.

Chrome Plugin: Available as a Chrome extension for auditing any webpage.

Web.dev: Offers comprehensive audits and recommendations using Lighthouse.

Google Lighthouse evaluates websites across five key categories:

Performance: Measures speed and responsiveness.

Accessibility: Assesses how well the site accommodates users with disabilities.

Best Practices: Checks adherence to modern web development standards and security practices.

SEO: Evaluates search engine optimization factors.

Progressive Web Apps (PWAs): Reviews PWA-specific features like offline functionality and service worker registration.

Lighthouse measures performance using several key metrics:

First Contentful Paint (FCP): Time until the first text or image is visible.

First Meaningful Paint (FMP): Time when the main content of the page is visible.

Speed Index: How quickly the content is visually displayed.

Time to Interactive (TTI): Time until the page is fully interactive.

First CPU Idle: When the page’s main thread activity is low enough to process user inputs.

Estimated Input Latency: Time for the app to respond to user inputs.

Lighthouse offers several recommendations to enhance performance, including:

Reduce render-blocking resources: Minimize JavaScript and CSS that block rendering.

Serve images in next-gen formats: Use formats like WebP for faster loading.

Enable text compression: Apply compression techniques such as Gzip or Brotli.

Defer unused CSS: Load only the CSS needed for initial page render.

Minify/compress CSS and JavaScript: Reduce file sizes to improve loading times.

Lighthouse checks best practices related to security and modern web standards, including:

Use of HTTPS: Ensures the site uses secure protocols.

Avoiding deprecated APIs: Identifies obsolete or insecure APIs.

Secure JavaScript libraries: Checks for vulnerabilities in third-party libraries.

Avoiding non-secure commands: Ensures safe use of JavaScript commands and practices.

Lighthouse assesses SEO by checking:

Mobile-friendliness: Ensures the site performs well on mobile devices.

Structured data: Verifies the correct use of structured data and tags like canonicals and hreflang.

Crawlability: Checks if pages are accessible to search engine bots and properly indexed.

Lighthouse evaluates accessibility by examining:

Text descriptions for images: Ensures all images have descriptive alt attributes.

Element labeling: Checks if buttons and links are properly labeled for screen readers.

Keyboard navigation: Verifies that interactive elements are accessible via keyboard.

Progressive Web Apps (PWAs) are web applications that offer a native app-like experience. Lighthouse evaluates PWAs by checking:

Service worker registration: Ensures the app can work offline.

Offline functionality: Verifies the app’s usability without an internet connection.

Web app manifest: Checks for a valid manifest file that defines app settings and appearance.

Lighthouse primarily conducts audits on individual URLs. However, for comprehensive domain-level analysis, tools like Searchmetrics utilize Lighthouse’s framework to evaluate entire websites, comparing performance and optimization levels against industry standards and competitors.