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Web Best Practices Audit

Audits and fixes web security, browser compatibility, and code quality using Lighthouse Best Practices as the baseline.

Dev & CodingIntermediate★ 2,856⑂ 250AI score 9/10Last updated: Aug 24, 2026

What it does

  • Runs an evidence-led Lighthouse Best Practices audit on the rendered page (Chrome DevTools MCP lighthouse_audit, with Lighthouse CLI as fallback).
  • Applies a security checklist: HTTPS/HSTS, CSP & Trusted Types, SRI, security headers, dependency vulnerabilities, DOM XSS sinks, cookies.
  • Checks compatibility: doctype, charset ordering, viewport, feature detection over UA sniffing, safe polyfill strategy (including the polyfill.io supply-chain lesson).
  • Improves code quality: console error handling, React error boundaries, listener cleanup via AbortController, hidden source maps, semantic and valid HTML.
  • Wraps up with four checklists (Security, Compatibility, Code quality, UX) and a tools table.

Who it's for

  • Front-end developers and web app maintainers
  • Teams standardizing pre-deploy quality/security gates
  • Anyone with a mediocre Lighthouse score who needs concrete fixes

Usage examples

  1. "Apply best practices to this page" → live audit, then targeted code fixes per failing item.
  2. "Run a security audit" → CSP, headers, npm audit, source-map exposure reviewed and reported.
  3. "Modernize this legacy code" → replaces document.write, sync XHR, and userAgent branching with modern APIs.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/addyosmani/web-quality-skills/HEAD/skills/best-practices/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the skills/best-practices folder from the GitHub repo addyosmani/web-quality-skills into my ~/.claude/skills/best-practices/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/addyosmani/web-quality-skills.git && mkdir -p ~/.claude/skills && cp -r web-quality-skills/skills/best-practices ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal.
  2. Clone the repo: git clone https://github.com/addyosmani/web-quality-skills.git
  3. Create the skills folder: mkdir -p ~/.claude/skills
  4. Copy the skill: cp -r web-quality-skills/skills/best-practices ~/.claude/skills/
  5. Confirm bundled files such as references/SECURITY.md came along.
  6. Restart Claude Code and ask it to "apply best practices" or "run a security audit".
  7. Optional: connect Chrome DevTools MCP, or install the CLI with npm i -g lighthouse, for live audits.
View source on GitHub ↗License: MIT