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          A U D I T O R

Lighthouse for design consistency

One command. 9 audit modules. A score from 0 to 100.

What is this?

design-auditor opens any website in a real Chromium browser, inspects every element's computed styles, and scores design consistency across 9 modules — typography, colors, spacing, components, readability, images, links, headings, and breakpoints.

npx design-auditor https://stripe.com

Think of it as Lighthouse, but for your design system — not performance, not SEO, but the visual coherence of your product.

| Tool | What it checks | | ------------------ | --------------------------------------------------------- | | Lighthouse | Performance, SEO, best practices | | axe / WAVE | Accessibility compliance | | Stylelint | CSS source code linting | | design-auditor | Design system consistency — the gap no one else fills |

See it in action

Quick Start

# No installation needed
npx design-auditor https://stripe.com

# Audit only specific modules
npx design-auditor https://stripe.com --only colors,typography

# Local dev server
npx design-auditor http://localhost:3000 --local

# Save JSON report for CI
npx design-auditor https://stripe.com --save-report

Scoring

Every audit produces a weighted score from 0 to 100 with a letter grade:

┌──────────────────────────────────────────────────┐
│                DESIGN AUDIT SCORE                │
│                                                  │
│          72 / 100  —  Grade B (Good)             │
│                                                  │
│  Typography        ████████░░  82   (weight 15%) │
│  Colors            ██████░░░░  60   (weight 20%) │
│  Rhythm & Spacing  ████████░░  78   (weight 15%) │
│  Components        ██████░░░░  65   (weight 15%) │
│  Reading Width     █████████░  90   (weight 10%) │
│  Images            ████████░░  80   (weight 10%) │
│  Links             █████████░  85   (weight  5%) │
│  Headings          ██████████  100  (weight  5%) │
│  Breakpoints       ███████░░░  70   (weight  5%) │
└──────────────────────────────────────────────────┘

| Grade | Score | Meaning | | ----- | ------ | ------------------------------------ | | A | 90-100 | Excellent — consistent design system | | B | 75-89 | Good — minor inconsistencies | | C | 60-74 | Needs Work — visible design drift | | D | 40-59 | Poor — significant inconsistencies | | F | 0-39 | Critical — no design system detected |

Use --save-report to track your score over time and catch design drift in CI.

9 Audit Modules

Typography weight: 15%

Good type is invisible. Bad type is everywhere.

• Font family count (recommended: ≤ 3)
• Unique font sizes and modular scale adherence
• Line-height consistency across text elements
• Outlier sizes that break the visual rhythm

Colors weight: 20%

A brand is not a logo. It's a consistent palette.

• Unique color count across the entire page
• Similar shade clustering using delta-E color science
• Auto-detection of primary / secondary / accent colors by usage frequency
• WCAG AA contrast validation for all text/background pairs
• CSS variable coverage — are colors tokenized or hardcoded?

Vertical Rhythm & Spacing weight: 15%

The baseline grid is the heartbeat of a layout.

• Rhythm unit detection (font-size x line-height)
• Line-heights as multiples of the rhythm unit
• 4px / 8px grid adherence for margins and paddings
• Outlier spacing values like 13px, 17px, 22px

Components weight: 15%

Inconsistent buttons are a symptom of an inconsistent system.

• Touch target sizes (minimum 44x44px per WCAG 2.5.5)
• Button padding variations (recommended: ≤ 3 sizes — sm/md/lg)
• :hover and :focus interactive states
• Border-radius system (recommended: ≤ 5 values)
• Box-shadow elevation levels and light direction consistency
• Z-index organization and "magic numbers"

Reading Width weight: 10%

If a line is too long, the reader's eye has a hard time finding the next line.

• Average line character count (optimal: 45-75 characters)
• Percentage of text blocks within optimal reading width
• Flags text containers that are too wide (>85 chars) or too narrow (<30 chars)

Images weight: 10%

Every image without alt text is a door slammed on a screen reader user.

• Alt text coverage (error if >30% missing)
• Aspect ratio consistency (recommended: ≤ 3 unique ratios)
• Inconsistent ratios within component groups (e.g. cards with mixed image proportions)

Links weight: 5%

A link distinguished only by color is invisible to 8% of men.

• WCAG 1.4.1 — links must not rely on color alone (needs underline or other indicator)
• Link color consistency across the page
• :visited state defined
• :focus state for keyboard navigation (WCAG 2.4.7)

Headings weight: 5%

Headings are the table of contents your DOM never knew it had.

• Exactly one <h1> per page
• Logical heading order (no skipped levels like H2 → H4)
• Visual size hierarchy — higher-level headings must appear larger
• Deep nesting warnings (excessive H5/H6 usage)

Breakpoints weight: 5%

A responsive design without a breakpoint system is just a flexible mess.

• Known system detection (Bootstrap, Tailwind, etc.)
• Breakpoint count (recommended: 4-6, error if >8)
• Strategy check — mobile-first vs desktop-first vs mixed
• Non-standard breakpoint values

Output

────────────────────────────────────────────────────────────
  TYPOGRAPHY
────────────────────────────────────────────────────────────
  ✅ Font families: 2 — OK
  ⚠️  Font sizes: 11 unique — recommended ≤ 8
     Found: 12px 14px 16px 18px 22px 24px 32px 40px 48px 56px 64px
  ❌ Line-heights: 22 unique — no vertical rhythm
     Too many line-height values — no baseline grid detected

  COLORS
────────────────────────────────────────────────────────────
  ❌ 54 unique colors found — recommended < 20
  ❌ 40 similar color pairs — palette can be consolidated
     ██ #f0f6fc ≈ ██ #f6f8fa (ΔE=2.6)
     ██ #24292f ≈ ██ #1f2328 (ΔE=2.9)
  ✅ Primary:   ██ #79c0ff  (262 uses)
  ✅ Secondary: ██ #59636e  (100 uses)
  ✅ Color balance: 63% / 24% / 2% — close to 60/30/10 rule

  COMPONENTS
────────────────────────────────────────────────────────────
  ❌ 28/50 buttons smaller than 44px touch target (56%)
     "Sign up" 101×32px, "Explore" 94×36px
  ⚠️  Buttons: 11 padding variations — recommended ≤ 3
  ✅ Interactive states: :hover and :focus present
  ❌ 12 unique border-radius values — recommended ≤ 5

────────────────────────────────────────────────────────────
  SCORE: 72 / 100 — Grade B (Good)
────────────────────────────────────────────────────────────

Every color is rendered as a live color swatch right in your terminal.

How it works

URL  →  Playwright opens a real Chromium browser
         │
         ├── page.evaluate()  ←  runs inside the browser
         │   └── getComputedStyle() on every element
         │       returns actual rendered values
         │
         ├── 9 Extractors collect raw data
         │   ├── typography.ts     — fonts, sizes, line-heights
         │   ├── colors.ts         — delta-E clustering, WCAG contrast
         │   ├── rhythm.ts         — spacing, margins, grid detection
         │   ├── components.ts     — buttons, shadows, z-index
         │   ├── reading-width.ts  — line character counts
         │   ├── images.ts         — alt text, aspect ratios
         │   ├── links.ts          — states, color-only distinction
         │   ├── headings.ts       — hierarchy, visual sizing
         │   └── breakpoints.ts    — media query analysis
         │
         ├── Rules engine evaluates violations (pass / warn / error)
         │
         └── Score calculator → weighted 0-100 score + grade

Unlike static CSS analysis, design-auditor uses a real browser — so it sees computed styles, not source code. It catches values injected by JavaScript, CSS custom properties resolved at runtime, and styles applied by third-party scripts.

Options

design-auditor <url> [options]

Arguments:
  url                    Website URL to audit

Options:
  --only <modules>       Run specific modules only
                         Values: typography, colors, spacing, components,
                         reading-width, images, links, headings, breakpoints
  --save-report          Save full report as JSON file
  --local                Optimize for local dev servers (disables networkidle)
  -V, --version          Show version number
  -h, --help             Show help

JSON Report

With --save-report, the full audit is saved as structured JSON — perfect for CI pipelines, dashboards, or tracking design drift over time.

{
  "url": "https://stripe.com",
  "date": "2026-02-27T10:00:00.000Z",
  "score": {
    "overall": 72,
    "grade": "B",
    "label": "Good"
  },
  "summary": {
    "pass": 7,
    "warn": 5,
    "error": 3
  },
  "modules": [
    {
      "name": "Colors",
      "score": 60,
      "weight": 20,
      "violations": [
        {
          "id": "too-many-colors",
          "severity": "error",
          "message": "54 unique colors found — recommended < 20",
          "hint": "A large palette makes maintenance harder..."
        }
      ]
    }
  ]
}

Design philosophy

A design system is a set of constraints. Audit tools should enforce them.

Most automated tools check if your site works (Lighthouse) or if it's accessible (axe). design-auditor checks if your site is consistent — the thing that's hardest to maintain as teams grow.

Based on established standards:

• WCAG 2.1 / 2.5.5 — touch targets, contrast ratios, link distinction
• 8-Point Grid System — spacing consistency
• Modular Scale — typographic hierarchy
• CIE delta-E — perceptual color similarity
• 60-30-10 rule — color balance

Installation

# Run without installing
npx design-auditor https://stripe.com

# Or install globally
npm install -g design-auditor
design-auditor https://stripe.com

Requirements: Node.js 18+

Contributing

Contributions are welcome! Whether it's a bug fix, a new audit rule, or an improvement to an existing module — open an issue or submit a PR.

git clone https://github.com/PashaSchool/design-auditor.git
cd design-auditor
npm install
npx playwright install chromium
npm run dev -- https://example.com

See open issues for ideas on where to start.

Limitations

• Audits only the first page at the given URL (no multi-page crawl yet)
• JavaScript-heavy SPAs may need a few seconds to fully render — use --local for dev servers
• Media query analysis reads CSS source rules; dynamically injected media queries may be missed
• Color extraction uses computed styles — colors set via canvas, svg, or background-image gradients are not captured

Security

All dependencies are continuously scanned for vulnerabilities using Snyk.

License

MIT — use it, fork it, build on it.

Built with care for designers who care about consistency.

Read the story behind design-auditor on dev.to