Lighthouse

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, SEO 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.

You can also use Lighthouse CI to prevent regressions on your sites.

Run Lighthouse In Chrome DevTools bug_report File an issue

Check out the video below from Google I/O 2019 to learn more about how to use and contribute to Lighthouse.

Get started

Choose the Lighthouse workflow that suits you best:

• In Chrome DevTools. Easily audit pages that require authentication, and read your reports in a user-friendly format.
• From the command line. Automate your Lighthouse runs via shell scripts.
• As a Node module. Integrate Lighthouse into your continuous integration systems.
• From a web UI. Run Lighthouse and link to reports without installing a thing.

Run Lighthouse in Chrome DevTools

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

1. Download Google Chrome for Desktop.
2. In Google Chrome, go to the URL you want to audit. You can audit any URL on the web.
3. Open Chrome DevTools.

4. Click the Audits tab.

   

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

6. Click Run audit. After 30 to 60 seconds, Lighthouse gives you a report on the page.

   

Install and run the Node command line tool

To install the Node module:

1. Download Google Chrome for Desktop.
2. Install the current Long-Term Support version of Node.

3. Install Lighthouse. The -g flag installs it as a global module.

   npm install -g lighthouse
   

To run an audit:

lighthouse <url>

To see all the options:

lighthouse --help

Run the Node module programmatically

See Using programmatically for an example of running Lighthouse programmatically, as a Node module.

Run Lighthouse as a Chrome Extension

To install the extension:

1. Download Google Chrome for Desktop.

2. Install the Lighthouse Chrome Extension from the Chrome Webstore.

To run an audit:

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

2. 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.

   

3. Click Generate report. Lighthouse runs its audits against the currently-focused page, then opens up a new tab with a report of the results.

   

Run PageSpeed Insights

To run Lighthouse on PageSpeed Insights:

1. Navigate to PageSpeed Insights.
2. Enter a web page URL.

3. Click Analyze.

   

Share and view reports online

Use the Lighthouse Viewer to view and share reports online.

Share reports as JSON

The Lighthouse Viewer needs the JSON output of a Lighthouse report. The list below explains how to get the JSON output, depending on what Lighthouse workflow you're using:

• Chrome DevTools. Click Download Report .

• Command line. Run:

  lighthouse --output json --output-path <path/for/output.json>

• Lighthouse Viewer. Click Export > Save as JSON.

To view the report data:

1. Open the Lighthouse Viewer in Google Chrome.
2. Drag the JSON file onto the viewer, or click anywhere on the Viewer to open your file navigator and select the file.

Share reports as GitHub Gists

If you don't want to manually pass around JSON files, you can also share your reports as secret GitHub Gists. One benefit of Gists is free version control.

To export a report as a Gist from the report:

1. (If already on the viewer, skip this step) Click Export > Open In Viewer. The report opens in the Viewer, located at https://googlechrome.github.io/lighthouse/viewer/.
2. In the Viewer, click Share . The first time you do this, a popup asks permission to access your basic GitHub data, and to read and write to your Gists.

To export a report as a Gist from the CLI version of Lighthouse, just manually create a Gist and copy-paste the report's JSON output into the Gist. The Gist filename containing the JSON output must end in .lighthouse.report.json. See Share reports as JSON for an example of how to generate JSON output from the command line tool.

To view a report that's been saved as a Gist:

• Add ?gist=<ID> to the Viewer's URL, where <ID> is the ID of the Gist.

  https://googlechrome.github.io/lighthouse/viewer/?gist=<ID>

• Open the Viewer, and paste the URL of a Gist into it.

Lighthouse extensibility

Lighthouse aims to provide guidance that is relevant and actionable for all web developers. To this end, there are two features now available that allow you to tailor Lighthouse to your specific needs.

• Stack Packs. Many developers today use different technologies (backend/CMS/JavaScript frameworks) to build their web pages. Instead of only surfacing general recommendations, Lighthouse is now able to provide more relevant and actionable advice depending on the tools used.

Stack Packs allow Lighthouse to detect what platform your site is built on and display specific stack-based recommendations. These recommendations are defined and curated by experts from the community.

To contribute a Stack Pack, review the Contributing Guidelines.

• Lighthouse Plugins. Lighthouse Plugins allow domain experts in the community to extend the functionality of Lighthouse for their specific needs. You are now able to leverage the data that Lighthouse collects to create new audits. At its core, a Lighthouse plugin is a node module that implements a set of checks that will be run by Lighthouse and added to the report as a new category.

For more information about how to create your own plugin, check out our Plugin Handbook in the Lighthouse GitHub repo.

Contribute to Lighthouse

Lighthouse is open source and contributions are welcome. Check out the repository's issue tracker to find bugs that you can fix, or audits that you can create or improve upon. The issues tracker is also a good place to discuss audit metrics, ideas for new audits, or anything else related to Lighthouse.