Web Page Performance : Knowledge Base

Lighthouse - https://developers.google.com/web/tools/lighthouse/#devtools

Lighthouse is an open-source, automated tool for improving the quality of web pages. You can run it against any web page, public or requiring authentication. It has audits for performance, accessibility, progressive web apps, and more.

You can run Lighthouse in Chrome DevTools, from the command line, or as a Node module. You give Lighthouse a URL to audit, it runs a series of audits against the page, and then it generates a report on how well the page did. From there, use the failing audits as indicators on how to improve the page. Each audit has a reference doc explaining why the audit is important, as well as how to fix it.

Check out the video below from Google I/O 2017 to learn more about how to use and contribute to Lighthouse.

Run Lighthouse in Chrome DevTools

Lighthouse now powers the Audits panel of Chrome DevTools. To run a report:

Download Google Chrome for Desktop.

In Google Chrome, go to the URL you want to audit. You can audit any URL on the web.

Open Chrome DevTools.

Click the Audits tab.

Figure 1. To the left is the viewport of the page that will be audited. To the right is the Audits panel of Chrome DevTools, which is now powered by Lighthouse

5.Click Perform an audit. DevTools shows you a list of audit categories. Leave them all enabled.

6. Click Run audit. After 60 to 90 seconds, Lighthouse gives you a report on the page.

Figure 2. A Lighthouse report in Chrome DevTools

To install the extension:

Download Google Chrome for Desktop.

Install the Lighthouse Chrome Extension from the Chrome Webstore.

To run an audit:

In Chrome, go to the page you want to audit.

Click Lighthouse . It should be next to the Chrome address bar. If not, open Chrome's main menu and access it at the top of the menu. After clicking, the Lighthouse menu expands.