Can Lighthouse be used for pages that require a login?

Yes, Lighthouse can audit pages that require authentication. When running it from Chrome DevTools, you can first log into the website in the same browser tab and then run the audit. The authenticated session will be used for the analysis.

What is the difference between Lighthouse and PageSpeed Insights?

Lighthouse is the underlying auditing engine that can be run in different environments (like your local browser's DevTools). PageSpeed Insights is a web-based tool that uses Lighthouse to run its analysis. A key difference is that PageSpeed Insights provides both lab data (from a Lighthouse run) and field data (real-user data from the Chrome User Experience Report), whereas a local Lighthouse run only provides lab data based on your machine's conditions.

Lighthouse

Beginner

An open-source, automated tool from Google for improving the quality of web pages. It audits performance, accessibility, progressive web apps, SEO, and more, providing a report with actionable insights.

First used·2016

Definitions·1

Synonyms·2

Category·Web Development

Also known as

Google LighthouseChrome Lighthouse

Definitions

What it means.

01
Web Quality Auditing Tool
Lighthouse is an open-source, automated tool developed by Google designed to improve the quality of web pages. It can be run against any web page, public or requiring authentication. It provides a comprehensive report across several key areas, often called categories.

Key Categories Audited:

Performance: Measures how quickly a page loads and becomes interactive. It analyzes metrics like First Contentful Paint (FCP), Speed Index, Largest Contentful Paint (LCP), Time to Interactive (TTI), Total Blocking Time (TBT), and Cumulative Layout Shift (CLS).

Accessibility (a11y): Checks for common issues that may prevent users with disabilities from accessing content. It provides a score and highlights opportunities for improvement, such as ensuring proper color contrast and ARIA attributes.

Best Practices: Audits for modern web development best practices, such as using HTTPS, avoiding deprecated APIs, and ensuring resources are served securely.

SEO (Search Engine Optimization): Performs basic checks to ensure a page is discoverable by search engines. It verifies things like the presence of a <title> tag, a meta description, and crawlable links.

Progressive Web App (PWA): Validates the aspects of a PWA, checking for a service worker, a web app manifest, and its ability to work offline.

How to Use Lighthouse:

In Chrome DevTools: The most common way. Open DevTools (F12 or Ctrl+Shift+I), go to the "Lighthouse" tab, and generate a report.

As a Chrome Extension: Provides a convenient button in the browser toolbar to run an audit.

From the Command Line (CLI): Useful for integrating Lighthouse into continuous integration (CI) systems. Developers can run npx lighthouse <url> to generate reports programmatically.

As a Node module: Allows for programmatic integration into build scripts and other tools.

Via PageSpeed Insights: Google's PageSpeed Insights online tool uses Lighthouse as its analysis engine to provide performance reports.

Origin

Where it comes from.

Etymology

The name "Lighthouse" is a metaphor. Just as a physical lighthouse guides ships safely to shore by illuminating the path and warning of dangers, Google's Lighthouse tool guides web developers to create better, safer, and more performant websites by illuminating issues and providing guidance for improvement.

Historical context

Lighthouse was first introduced by Google in 2016 as a tool primarily focused on auditing Progressive Web Apps (PWAs). It was initially available as a Chrome extension and a command-line tool. Its goal was to provide developers with a clear set of metrics and actionable advice to build high-quality PWAs that were reliable, fast, and engaging.

Over time, its scope expanded significantly. In 2017, with the release of Lighthouse v2, it integrated audits for performance, accessibility, and best practices, making it a more comprehensive web page quality tool. A major milestone was its integration directly into Chrome DevTools in 2018 (with Chrome 60), making it accessible to millions of developers without needing a separate extension.

Subsequent versions have continued to add more audits, refine scoring algorithms (like the introduction of Core Web Vitals), and improve the clarity of its reports, solidifying its position as an essential tool for modern web development.

Usage

In context.

The developer ran a Lighthouse audit to identify performance bottlenecks before the production launch.
Our team's goal is to achieve a Lighthouse accessibility score of over 90 for all our public-facing pages.
According to the Google Lighthouse report, we need to optimize our images to improve the Largest Contentful Paint time.
We integrated the Lighthouse CLI into our CI/CD pipeline to prevent performance regressions from being deployed.

FAQ

Common questions.

Lighthouse audits five main categories: Performance, Accessibility, Best Practices, SEO (Search Engine Optimization), and Progressive Web App (PWA).

Taxonomy

What it means.

Web Quality Auditing Tool

Where it comes from.

In context.

Common questions.

Filed under.