mcp-uimax
Runs full Google Lighthouse audits to provide real-time scores and detailed reports for performance, accessibility, best practices, and SEO, including fix instructions for identified issues.
UIMax MCP
Turns Claude Code into a frontend expert that reviews and fixes your UI automatically.
One command — "review my UI at localhost:3000" — and it:
Sees your app — captures a real screenshot via Puppeteer
Audits accessibility — runs axe-core for WCAG 2.1 violations
Runs Lighthouse — real Google Lighthouse scores (Performance, Accessibility, Best Practices, SEO)
Measures performance — captures Core Web Vitals (FCP, LCP, CLS, TBT)
Audits SEO — 18 checks: meta tags, Open Graph, Twitter cards, structured data, heading hierarchy, canonical URLs
Scans your code — AST-based analysis for 25+ anti-patterns across accessibility, design, and code quality
Grades everything — per-section Report Card with letter grades (A+ through F) for Accessibility, Performance, Best Practices, SEO, and Code Quality
Generates an expert review — Claude acts as a senior frontend engineer with a baked-in review methodology
Implements the fixes — edits your actual code files, starting from critical issues down
Tracks everything — auto-saves review history so you can see progress over time
Works on any URL — localhost, staging, production. Any site your machine can reach.
Free for all Claude Code users (Pro plan and above). No API keys. No extra costs. Just install and go.
claude mcp add uimax -- npx -y uimax-mcpQuick Start
Install as MCP Server (for Claude Code)
# Add to Claude Code — that's it, no API keys needed
claude mcp add uimax -- npx -y uimax-mcpThat's it. Now in any Claude Code conversation:
You: Review the UI at http://localhost:3000, source code is in ./src
Claude Code calls review_ui ->
1. Captures screenshot of your running app
2. Runs axe-core accessibility audit
3. Runs Google Lighthouse (Performance, A11y, Best Practices, SEO)
4. Measures Core Web Vitals
5. Runs dedicated SEO audit (18 checks)
6. Scans source code with AST-based analysis
7. Generates per-section Report Card (A+ through F letter grades)
8. Returns screenshot + all data + expert review methodology
9. Claude Code generates expert review (using YOUR Pro plan -- $0 extra)
10. Claude Code implements every fix automatically
11. Review saved to .uimax-reviews.json for trackingInstall Globally
npm install -g uimax-mcpRelated MCP server: WebSee MCP Server
Tools (37)
Review Pipeline
Tool | Description |
| The main tool. Full automated pipeline: screenshot + Lighthouse + axe-core + performance + SEO + code analysis + Report Card (A+-F letter grades) + expert review methodology. Auto-saves to review history. |
| New in v0.9.0. Re-run the full audit after applying fixes. Compares against the previous review and shows a before/after Report Card with grade transitions, resolved issue count, and verdict (improved/regressed/mixed). Closes the review-fix-verify loop. |
| New in v0.9.0. Competitive benchmarking — audit two URLs side-by-side. Returns screenshots of both sites plus a comparison Report Card with grades for Accessibility, Performance, SEO, and weighted Overall score. |
| Fast design-only review. Screenshot + focused design methodology. No code analysis or performance audit. |
| Generate a standalone HTML report with everything embedded. Now includes Report Card grade cards and SEO section. Dark themed, zero dependencies. Share with your team. |
Screenshots & Visual
Tool | Description |
| Capture a high-resolution PNG screenshot of any URL. |
| Screenshots at mobile (375px), tablet (768px), and desktop (1440px) viewports. |
| Compare light mode vs dark mode (emulated). Returns both screenshots + difference percentage. |
| Pixel-level diff using |
| AI-powered visual comparison. Captures before/after + pixel diff, returns structured methodology for Claude to evaluate whether changes match the intended design request. |
Lighthouse, Performance & SEO
Tool | Description |
| Full Google Lighthouse audit — Performance, Accessibility, Best Practices, SEO scores + failing audits. |
| New in v0.8.0. Dedicated SEO audit checking 18 signals: meta title/description, heading hierarchy, Open Graph, Twitter cards, structured data (JSON-LD), canonical URLs, image alt text, viewport meta, lang attribute, and more. Weighted scoring by impact. |
| PWA readiness: installable, service worker, HTTPS, manifest, offline capability. |
| Security analysis: HTTPS, CSP, mixed content, vulnerable JS libraries, external links without |
| Find unused JavaScript and CSS with exact byte savings per resource. |
| Deep LCP analysis: what the element is, resource load time, render delay, TTFB, optimization suggestions. |
| Full resource breakdown by type, transfer sizes, request count, top 10 largest, render-blocking resources. |
| Core Web Vitals via Performance API: FCP, LCP, CLS, TBT, DOM node count, JS heap size. |
| axe-core WCAG 2.1 Level A & AA audit. Violations grouped by severity with fix instructions. |
Code Analysis
Tool | Description |
| AST-based analysis (TypeScript compiler API) for 25+ rules. Zero false positives on string literals. Falls back to regex for non-JS files. Configurable via |
Browser Interaction
Tool | Description |
| Navigate to a URL, wait for network idle. Returns page info + screenshot. |
| Click an element by CSS selector. Returns screenshot after click. |
| Type into input fields. Options: |
| Select a dropdown option by value. Returns screenshot after. |
| Scroll by pixel amount or to a specific element. Returns screenshot after. |
| Wait for an element to appear in the DOM. Returns tag name and text content. |
| Get element details: attributes, bounding box, computed styles, visibility. |
Debugging
Tool | Description |
| Capture all console messages (log, warn, error, info, debug) + uncaught exceptions during page load. |
| Capture all network requests with status, size, timing, resource type. Summary grouped by type. |
| Capture JS exceptions, unhandled rejections, and failed resource loads. |
Multi-Page
Tool | Description |
| Discover internal links from a URL and audit up to 10 pages — screenshot + axe-core + performance each. |
Baselines & Budgets
Tool | Description |
| Save current audit state to |
| Compare current state vs previous baseline. Shows improvements and regressions with letter grade transitions (e.g., "D -> B+ (+22)"). |
| Enforce performance budgets from |
Review History
Tool | Description |
| View past UIMax reviews for this project. Filter by URL, limit count. Now includes letter grades alongside scores. |
| Aggregate statistics: total reviews, score trends, most common issues, most problematic files. Includes Code Quality grades. |
| Compare two specific reviews — new issues, resolved issues, score changes with letter grade transitions. |
Every review is auto-saved. When you run
review_ui, the results are automatically persisted to.uimax-reviews.json. No manual save needed — just ask "show me my review history" anytime.
Report Card (A+ through F)
Every review_ui run now generates a per-section Report Card with letter grades on a 13-tier scale:
┌─────────────────────────────────────────────────────┐
│ REPORT CARD │
├──────────────────┬──────────┬───────┬───────────────┤
│ Section │ Score │ Grade │ Rating │
├──────────────────┼──────────┼───────┼───────────────┤
│ Accessibility │ 95 │ A │ Excellent │
│ Performance │ 72 │ C- │ Below Average │
│ Best Practices │ 88 │ B+ │ Very Good │
│ SEO │ 61 │ D- │ Very Weak │
│ Code Quality │ 83 │ B │ Good │
└──────────────────┴──────────┴───────┴───────────────┘Grades appear in:
review_uioutput — Report Card table at the top of every reviewexport_reportHTML — color-coded grade cards (green A -> red F)compare_to_baseline— grade transitions showing improvement (e.g.,D -> B+ (+22))get_review_history/get_review_stats/review_diff— grades alongside numeric scores for quick scanning
The grading scale: A+ (97+) > A (93+) > A- (90+) > B+ (87+) > B (83+) > B- (80+) > C+ (77+) > C (73+) > C- (70+) > D+ (67+) > D (63+) > D- (60+) > F (<60)
AST-Powered Code Analysis
The analyze_code tool uses the TypeScript compiler API for .ts/.tsx/.js/.jsx files — catching bugs that regex misses with zero false positives.
Rule | What AST catches that regex misses |
| Hooks inside nested if/for/while/ternary — proper scope traversal |
|
|
| Empty catch blocks — not fooled by comments |
|
|
|
|
|
|
| JSX |
Falls back to regex for file types that can't be AST-parsed and for rules without AST implementations (hardcoded colors, z-index, font sizes, etc.).
Configuration
Create a .uimaxrc.json in your project root to customize code analysis and performance budgets:
{
"rules": {
"console-log": "off",
"magic-number": "off",
"hardcoded-color": "warn",
"inline-style": "error"
},
"severity": {
"todo-fixme": "high"
},
"ignore": [
"node_modules",
"dist",
"*.test.*",
"*.spec.*"
],
"budgets": {
"lighthouse": {
"performance": 90,
"accessibility": 95,
"bestPractices": 90,
"seo": 90
},
"webVitals": {
"fcp": 1800,
"lcp": 2500,
"cls": 0.1,
"tbt": 300
},
"maxAccessibilityViolations": 0,
"maxCodeIssues": 10
}
}rules— Set any rule to"off","warn", or"error"severity— Override severity:"low","medium","high","critical"ignore— Additional glob patterns to exclude from analysisbudgets— Performance thresholds enforced by thecheck_budgetstool
UIMax searches for .uimaxrc.json in the target directory and up to 3 parent directories, so it works in monorepos.
Prompts
Expert review prompts that guide Claude's analysis:
Prompt | Use Case |
| Comprehensive review (design + UX + a11y + perf + code) |
| Responsive design review across viewports |
| Fast visual/UX feedback from a screenshot only |
| AI-powered before/after visual comparison |
Example Workflows
Full Review (the main workflow)
You: Review the UI at http://localhost:3000
Source code is in ./src
Claude: [Calls review_ui]
[Captures screenshot, runs Lighthouse + axe + perf + code scan]
[Generates 20+ findings with specific fixes]
[Implements every fix automatically]
[Auto-saves review to .uimax-reviews.json]Review Any Public Website
You: Review the UI at https://stripe.com
Claude: [Calls review_ui]
[Full audit of the live production site]
[Returns findings + recommendations]Track Progress Over Time
You: Show me my review history
Claude: [Calls get_review_history]
[Shows table of past reviews: dates, scores, issue counts]
You: Compare my last two reviews
Claude: [Calls review_diff]
[Shows what improved ✅, what regressed ❌, new issues, resolved issues]
You: What are my most common issues?
Claude: [Calls get_review_stats]
[Shows trends, most common issues, most problematic files]Interact with Your App
You: Navigate to localhost:3000, click the login button,
type "test@email.com" in the email field
Claude: [Calls navigate → click → type_text]
[Returns a screenshot after each action]
[Verifies each step visually]Deep Performance Analysis
You: Find unused code on https://myapp.com
Claude: [Calls unused_code]
[Lists every unused JS/CSS file with byte savings]
[Suggests what to tree-shake]
You: Why is my LCP slow?
Claude: [Calls lcp_optimization]
[Identifies the LCP element, breakdown of load time]
[Specific optimization suggestions]Verify Fixes (Close the Loop)
You: Review and fix my UI at localhost:3000
Claude: [Calls review_ui → finds 14 issues → implements fixes]
You: Now verify the fixes worked
Claude: [Calls verify_fixes]
[Re-runs full audit → compares to previous review]
Fix Verification — Before vs After
| Metric | Before | After | Change |
| Accessibility violations | 5 | 0 | ✅ -5 |
| Code findings | 9 | 2 | ✅ -7 |
| Total issues | 14 | 2 | ✅ -12 |
Verdict: ✅ IMPROVEDCompetitive Benchmarking
You: Compare my site vs stripe.com
Claude: [Calls compare_sites]
[Audits both URLs concurrently]
[Returns screenshots of both sites + comparison table]
| Category | myapp.com | stripe.com | Winner |
| Accessibility | C+ (78) | A (94) | ✅ stripe.com |
| Performance | B- (81) | A+ (98) | ✅ stripe.com |
| SEO | D (63) | A (93) | ✅ stripe.com |
| Overall | C (74) | A (95) | ✅ stripe.com |SEO Audit
You: Run an SEO audit on https://myapp.com
Claude: [Calls seo_audit]
[Checks 18 SEO signals: meta tags, Open Graph, structured data, etc.]
[Returns score, passing checks, and failed checks with fix recommendations]
[Weighted by impact: critical > high > medium > low]Debug Page Load Issues
You: What console errors does localhost:3000 produce?
Claude: [Calls capture_console]
[Returns all console messages + uncaught exceptions]
You: Show me all network requests on page load
Claude: [Calls capture_network]
[Returns every request: URL, status, size, timing]
[Summary grouped by resource type]Before/After Comparison
You: Compare localhost:3000 with localhost:3001
Claude: [Calls compare_screenshots]
[Pixel-level diff with red-highlighted changes]
[Reports exact pixel difference %]Semantic Visual Review
You: I changed the header to be sticky. Compare before and after.
Claude: [Calls semantic_compare with change description]
[Captures both states + pixel diff]
[Evaluates whether changes match the intent]
[Checks for visual regressions]Enforce Performance Budgets
You: Check if my site meets our performance budgets
Claude: [Calls check_budgets]
[Reads thresholds from .uimaxrc.json]
[Returns ✅ pass or ❌ fail for each metric]Generate Shareable Report
You: Export a full report of localhost:3000 to ./report.html
Claude: [Calls export_report]
[Generates standalone dark-themed HTML report]
[Open in any browser, share with team]Multi-Page Audit
You: Crawl localhost:3000 and audit all pages
Claude: [Calls crawl_and_review]
[Discovers internal links, audits up to 10 pages]
[Per-page: screenshot + accessibility + performance]What Claude Reviews
When using the full review_ui pipeline, Claude evaluates:
Category | What's Checked |
Visual Design | Layout, typography, color contrast, whitespace, shadows, icon consistency |
User Experience | Navigation, interaction states, loading/error/empty states, edge cases |
Accessibility | WCAG 2.1 AA, keyboard nav, screen reader compat, focus management |
Performance | Lighthouse scores, Core Web Vitals, render-blocking resources, bundle size |
SEO | Meta tags, Open Graph, Twitter cards, structured data, heading hierarchy, canonical URLs, image alt text |
Code Quality | Component architecture, CSS organization, error boundaries, TypeScript safety |
Security | HTTPS, CSP, vulnerable libraries, mixed content |
Report Card | Per-section letter grades (A+ through F) for Accessibility, Performance, Best Practices, SEO, Code Quality |
Creative | Modern UI patterns (Linear, Vercel, Raycast), micro-interactions, animations |
Code Analysis Rules
The analyze_code tool checks for 25+ rules across categories:
Rule | Severity | Category |
| High | Accessibility |
| High | Accessibility |
| High | Accessibility |
| High | Accessibility |
| Medium | Accessibility |
| Medium | Accessibility |
| High | Code Quality |
| High | Code Quality |
| High | Bug |
| Low | Code Quality |
| Low | Code Quality |
| Medium | Code Quality |
| Medium | Code Quality |
| Low | Code Quality |
| Medium | Code Quality |
| Low | Code Quality |
| Medium | Design |
| Low | Design |
| Medium | Design |
| Medium | Design |
| Medium | Performance |
| Medium | Performance |
| Medium | UX |
| Medium | UX |
| Medium/High | Code Quality |
| Medium/High | Code Quality |
All rules can be toggled via .uimaxrc.json.
Supported Frameworks
Auto-detected from package.json:
React / Next.js
Vue / Nuxt
Svelte / SvelteKit
Angular
Plain HTML/CSS/JS
Requirements
Node.js >= 18.0.0
Chrome/Chromium (uses your system Chrome — no extra download)
Claude Code (for MCP integration)
No API keys needed — runs entirely within Claude Code using your existing Pro plan
How It Works
+----------------------------------------------------------------------+
| Claude Code (your Pro plan) |
| |
| User: "Review my UI at localhost:3000 and fix everything" |
| | |
| v |
| +----------------------------------------------------------------+ |
| | UIMax MCP (37 tools) | |
| | | |
| | Screenshot -------> Puppeteer ----------> PNG Image | |
| | Accessibility ----> axe-core ------------> WCAG Violations | |
| | Lighthouse -------> Google LH ----------> Scores + Audits | |
| | Deep LH ----------> PWA/Security/LCP --> Granular Analysis | |
| | SEO Audit --------> 18 checks ----------> SEO Score | |
| | Performance ------> Perf API ----------> Web Vitals | |
| | Code Scan --------> TypeScript AST -----> Anti-patterns | |
| | Report Card ------> Grading Engine -----> A+ to F Grades | |
| | Browser ----------> Click/Type/Scroll --> Interaction | |
| | Debugging --------> Console/Network ----> Runtime Data | |
| | History ----------> .uimax-reviews.json > Progress Tracking | |
| | Expert Prompt ----> Baked-in methodology | |
| +----------------------------+-----------------------------------+ |
| | |
| v |
| Claude Code receives: screenshot + data + expert methodology |
| | |
| v |
| Claude acts as world-class frontend expert (FREE -- Pro plan) |
| Generates comprehensive review with exact fixes |
| | |
| v |
| Claude implements every fix in the codebase automatically |
| |
+----------------------------------------------------------------------+CI / GitHub Action
UIMax ships with a reusable GitHub Action that runs audits on every PR and posts a Report Card comment.
Quick Setup
Copy the example workflow to your project:
# .github/workflows/uimax-ci.yml
name: UIMax Review
on:
pull_request:
branches: [main]
jobs:
uimax-review:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: actions/setup-node@v4
with:
node-version: "20"
# Build and start your app
- run: npm ci && npm run build
- run: npm start &
- run: npx wait-on http://localhost:3000
# Run UIMax
- uses: prembobby39-gif/uimax-mcp/.github/actions/uimax-review@main
with:
url: http://localhost:3000
budget-accessibility: 90
budget-performance: 80
budget-seo: 80
max-violations: 0Action Inputs
Input | Description | Required | Default |
| URL to audit | Yes | — |
| Token for PR comments | No |
|
| Min performance score (0-100) | No | — |
| Min accessibility score (0-100) | No | — |
| Min SEO score (0-100) | No | — |
| Max allowed a11y violations | No | — |
| Fail if grades regress | No |
|
Action Outputs
Output | Description |
| Letter grade (A+ through F) |
| Letter grade |
| Letter grade |
| Accessibility violation count |
| Whether all budgets passed ( |
| Full markdown report |
The action updates existing UIMax comments on re-push (no duplicate comments).
See examples/uimax-ci.yml for a complete working example.
Development
# Clone
git clone https://github.com/prembobby39-gif/uimax-mcp.git
cd uimax-mcp
# Install
npm install
# Build
npm run build
# Run tests
npm test
# Run tests with coverage
npm run test:coverage
# Test locally with Claude Code
claude mcp add uimax-dev -- node /path/to/uimax-mcp/dist/index.jsContributing
Contributions welcome! Some ideas:
CSS specificity analyzer
Design token extraction
Framework-specific checks (Vue composition API, Svelte stores)
Visual regression with pixel-level diffing
Performance budgets (fail if scores drop below thresholds)
Browser interaction (click, type, scroll, navigate)
Console and network capture
Deep Lighthouse analysis (PWA, security, unused code, LCP, resources)
AI-powered semantic visual comparison
Review history tracking with auto-save
Dedicated SEO audit (18 checks, weighted scoring)
Per-section letter grades (A+ through F Report Card)
Verify fixes (before/after comparison with grade transitions)
Competitive benchmarking (side-by-side site comparison)
CI/CD integration (GitHub Action for automated review on PR)
Custom rule plugins (user-defined regex rules)
Figma design comparison (screenshot vs Figma mock)
Cross-browser testing (Firefox, WebKit via Playwright)
License
MIT
Maintenance
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