Website Performance Analyzer Tool

Firefox DevTools panel that audits the current page and summarizes performance, accessibility, best practices, and SEO signals.

What it does

• Runs a fresh audit with a full reload (cache disabled).
• Scores categories and shows audit details inspired by Lighthouse.
• Breaks down JS, CSS, and other resource sizes.
• Exports the raw JSON report to the clipboard.

How to use

1. Open DevTools on any page.
2. Select the Performance panel.
3. Click Analyze to run a fresh audit (the page reloads without cache).

Key metrics

• TTFB, FCP, LCP, CLS, TBT
• DOMContentLoaded and Load timings
• Total transfer size and resource count

Audits

• Accessibility checks (image alt, button/link names, form labels)
• Best practices (HTTPS, mixed content, doctype, viewport, image sizes)
• SEO basics (title, meta description, canonical, indexable)

Installation

1. Open about:debugging#/runtime/this-firefox.
2. Click Load Temporary Add-on....
3. Select manifest.json from this folder.

Privacy

All analysis runs locally in the browser. No data is sent to external services.

Notes

• Works in Firefox DevTools (78+).