# BeaverCheck Audit Report — https://fourmilab.ch

**Date:** April 22, 2026  
**URL:** https://fourmilab.ch  
**Overall Grade:** C (74/100)  
**Report:** https://beavercheck.com/results/a50c0d4d-2f31-4ae5-9f8f-5fee37379842

## Top Findings

1. **[CRITICAL]** Content-Security-Policy header is missing — Security > Security Headers
2. **[CRITICAL]** No Content-Security-Policy header found — Security > Content Security Policy
3. **[WARNING]** Cross-Origin-Embedder-Policy header is missing — Security > Security Headers
4. **[WARNING]** Cross-Origin-Opener-Policy header is missing — Security > Security Headers
5. **[WARNING]** DMARC policy is none — monitoring only — Security > Email Security

---

## Lighthouse Scores

| Category | Score |
|----------|-------|
| Performance | 0 |
| Accessibility | 71 |
| Best Practices | 96 |
| SEO | 91 |

---

## Security

### Security Headers (F — 25/100)

*2 of 10 headers properly configured*

- **[PASS]** Strict-Transport-Security is properly configured (consider adding preload)
- **[WARNING]** X-Content-Type-Options header is missing — This header prevents MIME-type sniffing, which can lead to XSS attacks. Set it to 'nosniff'.
- **[WARNING]** X-Frame-Options header is missing — This header prevents clickjacking by controlling who can embed your page in a frame. Set it to DENY or SAMEORIGIN.
- **[WARNING]** Referrer-Policy header is missing — Controls how much referrer information is sent with requests. Set to 'strict-origin-when-cross-origin' or stricter.
- **[WARNING]** Permissions-Policy header is missing — Controls which browser features (camera, microphone, geolocation) are allowed. Set it to restrict unused features.
- **[CRITICAL]** Content-Security-Policy header is missing — CSP is the most important header for preventing XSS attacks. See the CSP section for detailed analysis.
- **[WARNING]** Cross-Origin-Opener-Policy header is missing — COOP isolates your browsing context, preventing cross-origin side-channel attacks. Set to 'same-origin'.
- **[WARNING]** Cross-Origin-Embedder-Policy header is missing — COEP prevents loading cross-origin resources without explicit permission. Required for SharedArrayBuffer and high-resolution timers.
- **[PASS]** X-Powered-By header is not present
- **[WARNING]** Server header reveals version information — The Server header discloses the software version, aiding attackers in targeting known vulnerabilities. Remove the version number.

### Content Security Policy (F — 0/100)

*No enforcing CSP policy found*

- **[CRITICAL]** No Content-Security-Policy header found — CSP is the most effective defense against XSS attacks. Add a Content-Security-Policy header to restrict resource loading.

### TLS & Certificates (A+ — 100/100)

*TLS 1.3, 7 checks passed*

- **[PASS]** TLS 1.3 is used
- **[PASS]** Strong cipher suite is used
- **[INFO]** HTTP/2 is not negotiated — HTTP/2 provides multiplexing and header compression for better performance.
- **[PASS]** Certificate is valid (expires in 69 days)
- **[PASS]** Certificate chain has 2 certificates
- **[PASS]** Certificate uses modern signature algorithm
- **[PASS]** Certificate covers 2 domain(s)
- **[PASS]** Certificate is issued by a trusted CA

### Cookie Security (A+ — 100/100)

*No cookies set — no cookie security risks*

- **[PASS]** No cookies set — no cookie security risks

---

## Advanced Security

### Subresource Integrity (A+ — 100/100)

*No external resources*

- **[PASS]** No external resources to protect

### JS Library Vulnerabilities (A+ — 100/100)

*No known vulnerabilities*

- **[PASS]** No known JavaScript library vulnerabilities detected

### Information Leakage (A+ — 100/100)

*No exposures*

- **[INFO]** No security.txt found — Consider adding a security.txt at /.well-known/security.txt.
- **[PASS]** No sensitive files exposed

### Email Security (D — 50/100)

*DMARC: none*

- **[WARNING]** DMARC policy is none — monitoring only — This only monitors, it doesn't block spoofed emails. Change to p=quarantine or p=reject.

### Permissions-Policy (D — 40/100)

*No header set*

- **[WARNING]** No Permissions-Policy header — Consider adding a Permissions-Policy header to restrict browser feature access from embedded content.

### CORS Configuration (B — 80/100)

*No CORS headers*

- **[PASS]** No CORS headers present — secure default

---

## Performance

### Page Weight Budget (A+ — 100/100)

*22 KB transferred, 17 requests*

- **[PASS]** Page weighs 40 KB (22 KB transferred)
- **[PASS]** 17 HTTP requests
- **[INFO]** Estimated 0.00 g CO2 per page load

### Third-Party Impact (A+ — 100/100)

*No third-party resources*

- **[PASS]** No third-party resources detected

### Text Compression (A+ — 100/100)

*All text resources are compressed*

- **[PASS]** All text resources are compressed

### Image Optimization (B — 75/100)

*8 images, 0 KB saveable*

- **[PASS]** All images are well-optimized

### JS Execution Cost (A+ — 100/100)

*290ms total JS execution*

- **[INFO]** Unattributable: 222ms CPU time
- **[INFO]** https://fourmilab.ch/nav/topics/welcome_ch.html: 68ms CPU time
- **[WARNING]** Third-party scripts: 222ms (77% of total)

### Font Loading (A+ — 100/100)

*No web fonts (system fonts)*

- **[PASS]** No web fonts loaded — system fonts are fastest

### JS Bundles (A+ — 100/100)

*No JavaScript*

- **[PASS]** No JavaScript bundles

### Resource Caching (A+ — 100/100)

*All resources properly cached*

- **[PASS]** No caching issues found

### Critical Rendering Path (A+ — 100/100)

*No render-blocking resources*

- **[PASS]** No render-blocking resources detected

### Resource Hints (A+ — 100/100)

*No optimization needed*

- **[PASS]** No resource hint issues

### Page Weight Inventory (A+ — 100/100)

*17 resources · 22 KB · 0 KB savings available*

- **[PASS]** Within 1MB page-weight target

---

## Infrastructure

### DNS Records (A+ — 95/100)

*1 A records, 79 ms lookup*

- **[PASS]** Resolves to 1 IPv4 address(es)
- **[INFO]** Single A record — no DNS redundancy — Multiple A records provide failover if one server goes down.
- **[PASS]** Has 1 IPv6 (AAAA) record(s)
- **[PASS]** 4 nameserver(s) configured
- **[PASS]** 5 mail exchanger(s) configured
- **[INFO]** CAA records not checked — CAA record lookup requires a specialized DNS resolver. This check will be available in a future update.
- **[PASS]** SPF record present in TXT
- **[PASS]** DNS resolution time: 79 ms

### Redirect Chain (A+ — 100/100)

*No redirects — direct access*

- **[PASS]** No redirects — direct access

### IPv6 Readiness (A+ — 100/100)

*IPv6 reachable (33 ms)*

- **[PASS]** IPv6 is configured and reachable at 2a05:d014:d43:3101:94aa:a276:e035:6a2a

### Crawlability (B — 80/100)

*robots.txt present, no sitemap*

- **[PASS]** robots.txt is present
- **[INFO]** No sitemap.xml found — A sitemap helps search engines discover and index your pages more efficiently.
- **[INFO]** robots.txt does not reference a sitemap — Add a 'Sitemap:' directive to robots.txt so search engines can discover your sitemap.

### URL Variants (B — 75/100)

*www/non-www, trailing slash, HTTP→HTTPS*

- **[CRITICAL]** Both www and non-www versions serve content
- **[PASS]** HTTP correctly 301-redirects to HTTPS

### Domain Intelligence

*Domain intelligence data not available*


---

## Compliance

### WCAG Compliance (A+ — 100/100)

*No testable criteria*


### Cookie Consent & Privacy (B — 80/100)

*No consent signals detected*

- **[WARNING]** No privacy policy link detected — A privacy policy page is recommended for transparency and may be legally required.
- **[INFO]** No terms of service link detected
- **[INFO]** No cookie consent banner detected
- **[INFO]** This is an automated check, not legal advice — BeaverCheck detects technical indicators of consent management. This does not constitute a legal compliance assessment. Consult a privacy professional for GDPR/CCPA compliance.

### Language & i18n (A — 90/100)

*Lang attribute present*

- **[PASS]** <html lang> attribute is present
- **[PASS]** <html lang> value is valid
- **[INFO]** No Content-Language HTTP header
- **[INFO]** Language signals are inconsistent — The <html lang> attribute and Content-Language header should agree.

### Readability & Typography (A+ — 100/100)

*Font sizes and tap targets checked*


### Viewport Configuration (F — 30/100)

*No viewport meta tag*

- **[CRITICAL]** No viewport meta tag found — Without a viewport meta tag, the page will not render correctly on mobile devices.

### Third-Party Trackers (A+ — 100/100)

*No third-party trackers detected*

- **[PASS]** No third-party trackers detected

---

## Availability

### CDN & Delivery (D — 50/100)

*No CDN detected*

- **[WARNING]** No CDN detected — A CDN can significantly improve load times for users around the world by caching content at edge nodes closer to them.

### HTTP Caching (D — 40/100)

*No cache headers*

- **[WARNING]** No Cache-Control header found — Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.
- **[PASS]** ETag present — enables conditional (304) responses
- **[PASS]** Last-Modified header present

### Transport Security (A — 90/100)

*HTTP/3, HSTS, and TLS version analysis*

- **[INFO]** HTTP/3 (QUIC) not advertised — HTTP/3 eliminates head-of-line blocking. If your CDN supports it, consider enabling it.
- **[PASS]** HSTS enabled (includeSubDomains)
- **[PASS]** TLS 1.3 in use (fastest handshake, 1-RTT)

---

## UX

### 404 Error Page (F — 35/100)

*HTTP 404, bare page*

- **[PASS]** Correct 404 status code returned
- **[WARNING]** Bare server default 404 page — The 404 page has no custom styling. Users hitting a broken link see a generic error with no way to navigate back. Add a custom 404 page with your site navigation and a search bar.

### Favicon & Branding (F — 15/100)

*1 icon(s) detected*

- **[PASS]** favicon.ico present at site root
- **[INFO]** No apple-touch-icon detected — iOS devices use this when users add your site to their home screen. Add <link rel='apple-touch-icon' sizes='180x180' href='/apple-touch-icon.png'>.

### Web Manifest (D — 40/100)

*Not found*

- **[INFO]** No web manifest found — No manifest at standard paths (/manifest.json, /site.webmanifest). A manifest is optional but enables PWA features like home screen installation and standalone display.

### Dark Mode Support (D — 40/100)

*No dark mode signals*

- **[INFO]** No dark mode signals detected — Consider adding CSS with @media (prefers-color-scheme: dark) and <meta name='color-scheme' content='light dark'>.
- **[INFO]** Detection limited to meta tags and inline styles — External CSS files may contain prefers-color-scheme rules not visible to this scan.

### Print Stylesheet (D — 40/100)

*No print styles*

- **[INFO]** No print-specific styles detected — When users print this page, they get the screen layout including navigation and non-essential elements. Add @media print rules to hide navigation and optimize layout for paper.

### Navigation UX (F — 0/100)

*No navigation patterns*

- **[INFO]** No breadcrumbs, search, or skip link detected — These navigation aids help users orient themselves and find content efficiently, especially on large sites.

---

## Sustainability

### CO2 Per Page Load (A+ — 100/100)

*0.01g CO2 per view*

- **[PASS]** 0.01g CO2 per page view — This page transfers 0.0 MB, producing an estimated 0.01g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.00g, network 0.00g, end-user device 0.00g.
- **[INFO]** At 10,000 monthly views: 0.7 kg CO2/year — With 10,000 page views per month, this page would generate approximately 0.7 kg of CO2 annually — equivalent to charging 91 smartphones.

### Green Hosting (D — 40/100)

*Not green*

- **[INFO]** No confirmed renewable energy commitment detected — Consider providers like Cloudflare, Google Cloud, or Vercel that match 100% of their energy use with renewables.
- **[INFO]** Green hosting status based on known provider commitments — Green hosting detection uses a curated database of provider renewable energy commitments. This is not a real-time verification. For authoritative checks, visit thegreenwebfoundation.org.

### Repeat Visit Weight (B — 80/100)

*72% cached*

- **[PASS]** 72% reduction on repeat visits — Returning visitors download only 6 KB (vs 22 KB first visit). 12 of 17 resources are served from browser cache, saving 0.00g CO2 per repeat visit.
- **[INFO]** Repeat visit: 0.00g CO2 (first visit: 0.01g)

### Carbon Budget (A+ — 100/100)

*10th percentile*

- **[PASS]** 0.01g CO2 — below the sustainability target of 0.50g — Cleaner than an estimated 90% of websites analyzed. This page meets the Web Sustainability Guidelines target.
- **[INFO]** Estimated 10th percentile — Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.

### Transfer Efficiency (A+ — 100/100)

*100% efficient*

- **[PASS]** Transfer efficiency: 100% — Only 0 KB of potential savings identified. Your page is well-optimized for size.

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*Generated by [BeaverCheck](https://beavercheck.com) — https://beavercheck.com/results/a50c0d4d-2f31-4ae5-9f8f-5fee37379842*