web-quality-audit

Comprehensive web quality audit covering performance, accessibility, SEO, best practices, and browser automation testing. Supports automated testing with PinchTab for headless/headed browser control, multi-instance orchestration, and token-efficient content extraction.

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Install skill "web-quality-audit" with this command: npx skills add web-quality-skills/web-quality-audit-ecc

Web Quality Audit

Comprehensive quality review based on Google Lighthouse audits. Covers Performance, Accessibility, SEO, and Best Practices across 150+ checks. Includes browser automation testing with PinchTab for real-world validation.

How it works

  1. Analyze the provided code/project for quality issues
  2. Categorize findings by severity (Critical, High, Medium, Low)
  3. Provide specific, actionable recommendations
  4. Include code examples for fixes
  5. NEW: Validate with browser automation (PinchTab) for real-world testing

Audit categories

Performance (40% of typical issues)

Core Web Vitals — Must pass for good page experience:

  • LCP (Largest Contentful Paint) < 2.5s. The largest visible element must render quickly. Optimize images, fonts, and server response time.
  • INP (Interaction to Next Paint) < 200ms. User interactions must feel instant. Reduce JavaScript execution time and break up long tasks.
  • CLS (Cumulative Layout Shift) < 0.1. Content must not jump around. Set explicit dimensions on images, embeds, and ads.

Resource Optimization:

  • Compress images. Use WebP/AVIF with fallbacks. Serve correctly sized images via srcset.
  • Minimize JavaScript. Remove unused code. Use code splitting. Defer non-critical scripts.
  • Optimize CSS. Extract critical CSS. Remove unused styles. Avoid @import.
  • Efficient fonts. Use font-display: swap. Preload critical fonts. Subset to needed characters.

Loading Strategy:

  • Preconnect to origins. Add <link rel="preconnect"> for third-party domains.
  • Preload critical assets. LCP images, fonts, and above-fold CSS.
  • Lazy load below-fold content. Images, iframes, and heavy components.
  • Cache effectively. Long cache TTLs for static assets. Immutable caching for hashed files.

Accessibility (30% of typical issues)

Perceivable:

  • Text alternatives. Every <img> has meaningful alt text. Decorative images use alt="".
  • Color contrast. Minimum 4.5:1 for normal text, 3:1 for large text (WCAG AA).
  • Don't rely on color alone. Use icons, patterns, or text alongside color indicators.
  • Captions and transcripts. Video has captions. Audio has transcripts.

Operable:

  • Keyboard accessible. All functionality available via keyboard. No keyboard traps.
  • Focus visible. Clear focus indicators on all interactive elements.
  • Skip links. Provide "Skip to main content" for keyboard users.
  • Sufficient time. Users can extend time limits. No auto-advancing content without controls.

Understandable:

  • Page language. Set lang attribute on <html>.
  • Consistent navigation. Same navigation structure across pages.
  • Error identification. Form errors clearly described and associated with fields.
  • Labels and instructions. All form inputs have associated labels.

Robust:

  • Valid HTML. No duplicate IDs. Properly nested elements.
  • ARIA used correctly. Prefer native elements. ARIA roles match behavior.
  • Name, role, value. Interactive elements have accessible names and correct roles.

SEO (15% of typical issues)

Crawlability:

  • Valid robots.txt. Doesn't block important resources.
  • XML sitemap. Lists all important pages. Submitted to Search Console.
  • Canonical URLs. Prevent duplicate content issues.
  • No noindex on important pages. Check meta robots and headers.

On-Page SEO:

  • Unique title tags. 50-60 characters. Primary keyword included.
  • Meta descriptions. 150-160 characters. Compelling and unique.
  • Heading hierarchy. Single <h1>. Logical heading structure.
  • Descriptive link text. Not "click here" or "read more".

Technical SEO:

  • Mobile-friendly. Responsive design. Tap targets ≥ 48px.
  • HTTPS. Secure connection required.
  • Fast loading. Performance directly impacts ranking.
  • Structured data. JSON-LD for rich snippets (Article, Product, FAQ, etc.).

Best practices (15% of typical issues)

Security:

  • HTTPS everywhere. No mixed content. HSTS enabled.
  • No vulnerable libraries. Keep dependencies updated.
  • CSP headers. Content Security Policy to prevent XSS.
  • No exposed source maps. In production builds.

Modern Standards:

  • No deprecated APIs. Replace document.write, synchronous XHR, etc.
  • Valid doctype. Use <!DOCTYPE html>.
  • Charset declared. <meta charset="UTF-8"> as first element in <head>.
  • No browser errors. Clean console. No CORS issues.

UX Patterns:

  • No intrusive interstitials. Especially on mobile.
  • Clear permission requests. Only ask when needed, with context.
  • No misleading buttons. Buttons do what they say.

Severity levels

LevelDescriptionAction
CriticalSecurity vulnerabilities, complete failuresFix immediately
HighCore Web Vitals failures, major a11y barriersFix before launch
MediumPerformance opportunities, SEO improvementsFix within sprint
LowMinor optimizations, code qualityFix when convenient

Audit output format

When performing an audit, structure findings as:

## Audit results

### Critical issues (X found)
- **[Category]** Issue description. File: `path/to/file.js:123`
  - **Impact:** Why this matters
  - **Fix:** Specific code change or recommendation

### High priority (X found)
...

### Summary
- Performance: X issues (Y critical)
- Accessibility: X issues (Y critical)
- SEO: X issues
- Best Practices: X issues

### Recommended priority
1. First fix this because...
2. Then address...
3. Finally optimize...

Quick checklist

Before every deploy

  • Core Web Vitals passing
  • No accessibility errors (axe/Lighthouse)
  • No console errors
  • HTTPS working
  • Meta tags present

Weekly review

  • Check Search Console for issues
  • Review Core Web Vitals trends
  • Update dependencies
  • Test with screen reader

Monthly deep dive

  • Full Lighthouse audit
  • Performance profiling
  • Accessibility audit with real users
  • SEO keyword review
  • Browser automation regression tests (PinchTab)

Browser Automation Testing (PinchTab)

PinchTab is a high-performance browser automation bridge for AI agents. Use it to validate your site in real browsers.

What is PinchTab?

  • Standalone HTTP server — Control Chrome via HTTP API
  • Token-efficient — 800 tokens/page with text extraction (vs 10,000+ for screenshots)
  • Multi-instance — Run multiple parallel Chrome processes
  • Headless or Headed — Run with or without visible window
  • Self-contained — 12MB binary, no dependencies
  • MCP integration — Native support via SMCP plugin

Installation

# macOS / Linux
curl -fsSL https://pinchtab.com/install.sh | bash

# npm
npm install -g pinchtab

# Docker
docker run -d -p 9867:9867 pinchtab/pinchtab

Start Server

# Terminal 1: Start PinchTab server
pinchtab
# Server runs on http://localhost:9867

Basic Usage

Navigate and Snapshot

# Navigate to URL
pinchtab nav https://example.com

# Wait 3 seconds for accessibility tree to populate
sleep 3

# Get interactive elements snapshot
pinchtab snap -i -c

Text Extraction (Token-Efficient)

# Extract text (~800 tokens vs 10,000+ for screenshots)
pinchtab nav https://example.com/article
sleep 3
pinchtab text

Click and Interact

# Get snapshot with element refs
pinchtab snap -i
# Output shows: e5: "Submit button", e12: "Email input"

# Click element by ref
pinchtab click e5

# Fill input
pinchtab fill e12 "user@example.com"

# Press key
pinchtab press e12 Enter

HTTP API

# Create instance
TAB=$(curl -s -X POST http://localhost:9867/instances \
  -d '{"profile":"work"}' | jq -r '.id')

# Navigate
curl -X POST "http://localhost:9867/instances/$TAB/tabs/open" \
  -d '{"url":"https://example.com"}'

# Get snapshot (wait 3s first)
sleep 3
curl "http://localhost:9867/instances/$TAB/snapshot?filter=interactive"

# Click element
curl -X POST "http://localhost:9867/instances/$TAB/action" \
  -d '{"kind":"click","ref":"e5"}'

# Extract text
curl "http://localhost:9867/instances/$TAB/text"

Web Quality Audit Patterns

1. Core Web Vitals Validation

#!/bin/bash
# validate-cwv.sh

URL=${1:-"https://example.com"}
INST=$(curl -s -X POST http://localhost:9867/instances \
  -d '{"mode":"headless"}' | jq -r '.id')

# Navigate and measure load time
START=$(date +%s%N)
curl -s -X POST "http://localhost:9867/instances/$INST/tabs/open" \
  -d "{\"url\":\"$URL\"}" > /dev/null
sleep 3
END=$(date +%s%N)

# Calculate LCP estimate (simplified)
LOAD_TIME=$(( (END - START) / 1000000 ))  # ms
echo "Estimated LCP: ${LOAD_TIME}ms"

# Check if < 2.5s
if [ $LOAD_TIME -lt 2500 ]; then
  echo "✅ LCP passing"
else
  echo "❌ LCP failing (> 2.5s)"
fi

# Cleanup
curl -s -X POST "http://localhost:9867/instances/$INST/stop" > /dev/null

2. Accessibility Tree Validation

# Get accessibility tree and check for common issues
pinchtab nav https://example.com
sleep 3

# Check for images without alt text
pinchtab snap | jq '.nodes[] | select(.role == "image" and .name == null) | {ref, role}'

# Check for buttons without labels
pinchtab snap | jq '.nodes[] | select(.role == "button" and .name == null) | {ref, role}'

# Check heading hierarchy
pinchtab snap | jq '.nodes[] | select(.role | startswith("heading")) | {role, name}'

3. Mobile Responsiveness Check

# Create headed instance for visual inspection
pinchtab instances create --profile=mobile-test --mode=headed

# Navigate to site
pinchtab nav https://example.com

# Take screenshot for manual review
pinchtab screenshot --output=mobile-test.png

# Check viewport meta tag
pinchtab evaluate "document.querySelector('meta[name=viewport]')?.content"

4. SEO Validation

# Extract page metadata
pinchtab nav https://example.com
sleep 2

# Get title
curl -s http://localhost:9867/instances/$INST/text | jq -r '.title'

# Get meta description (via evaluate)
pinchtab evaluate '
  document.querySelector("meta[name=description]")?.content
'

# Check for structured data
pinchtab evaluate '
  JSON.parse(document.querySelector("script[type=application/ld+json]")?.innerText || "{}")
'

Agent Optimization Tips

Based on PinchTab documentation:

The 3-Second Wait Rule

# ❌ Too fast - accessibility tree not ready
pinchtab nav https://example.com
pinchtab snap
# Returns: {"count": 1, "nodes": [{"ref": "e0", "role": "RootWebArea"}]}

# ✅ Wait 3 seconds for full tree
pinchtab nav https://example.com
sleep 3
pinchtab snap
# Returns: {"count": 2645, "nodes": [...]}

Token-Efficient Extraction Pattern

# Navigate + wait + filter (14x more token-efficient)
curl -X POST http://localhost:9867/navigate \
  -d '{"url": "https://example.com"}' && \
sleep 3 && \
curl http://localhost:9867/snapshot | \
jq '.nodes[] | select(.name | length > 15) | .name' | \
head -30

Why this works:

  1. Navigate + wait ensures full accessibility tree
  2. jq filter extracts text nodes only
  3. length > 15 filters out buttons, labels
  4. head -30 limits output (saves tokens)

Multi-Instance Testing

#!/bin/bash
# parallel-test.sh

URLS=("https://site1.com" "https://site2.com" "https://site3.com")
INSTANCES=()

# Create 3 headless instances
for i in {0..2}; do
  INST=$(curl -s -X POST http://localhost:9867/instances \
    -d '{"mode":"headless"}' | jq -r '.id')
  INSTANCES[$i]=$INST
done

# Run tests in parallel
for i in {0..2}; do
  (
    curl -s -X POST "http://localhost:9867/instances/${INSTANCES[$i]}/tabs/open" \
      -d "{\"url\":\"${URLS[$i]}\"}"
    sleep 3
    TITLE=$(curl -s "http://localhost:9867/instances/${INSTANCES[$i]}/text" | jq -r '.title')
    echo "Site $i: $TITLE"
    curl -s -X POST "http://localhost:9867/instances/${INSTANCES[$i]}/stop"
  ) &
done

wait
echo "All tests complete"

MCP Integration

PinchTab provides an SMCP plugin for Claude Code integration:

# Set plugin directory
export MCP_PLUGINS_DIR=/path/to/pinchtab/plugins

# Available tools:
# - pinchtab__navigate
# - pinchtab__snapshot
# - pinchtab__action
# - pinchtab__text
# - pinchtab__screenshot
# - pinchtab__evaluate
# etc.

Headless vs Headed

ModeUse CaseMemorySpeed
HeadlessCI/CD, scraping, batch~50-80 MBFast
HeadedDebugging, visual QA~100-150 MBSlower
# Headless for production
pinchtab instances create --mode=headless

# Headed for debugging
pinchtab instances create --mode=headed

References

For detailed guidelines on specific areas:

External Resources

Combine static analysis with real browser automation for comprehensive quality assurance.

Source Transparency

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