How to use Lighthouse for an audit?

Here is how to use Lighthouse for a site audit, step by step, without the filler:

#1. Open the site in Chrome

Go to the page you want to test. It is better to use incognito mode, without extensions, since they can distort the result.

#2. Open DevTools

• Right-click -> Inspect or
• Ctrl + Shift + I (Windows) / Cmd + Option + I (Mac)

#3. Go to the Lighthouse tab

In the developer panel, find the Lighthouse tab. If it is not there, click >> in the top right of the panel and select it there.

#4. Choose the audit parameters

• Mobile or desktop;
• What to analyze: Performance, SEO, Accessibility, Best Practices, PWA;
• Usually it is enough to check everything except PWA (unless it is a web app).

#5. Click "Analyze" / "Generate report"

Lighthouse will run a page load simulation and, after a few seconds, show a detailed report.

#6. Study the results

There you will find:

• Scores on a 100-point scale;
• Core Web Vitals;
• Details on what is slowing down loading, which tags are missing, which images can be compressed, and so on.

#7. Save or export

You can export the report as JSON or HTML (for example, to send it to a developer).

Lighthouse is a "one-button" audit. It does not fix problems, but it clearly shows where to dig.