40 checks in Technical Foundation & Rendering. Automated Its subsection has a live automated checker in the engine.
| ID | Check | Passes when |
|---|---|---|
| 1.4.01 | Capture full HAR file for page load | HAR saved successfully |
| 1.4.02 | Count total number of requests | < 120 requests |
| 1.4.03 | Count number of image requests | Reasonable (< 60) |
| 1.4.04 | Count number of JS requests | < 20 |
| 1.4.05 | Count number of CSS requests | < 10 |
| 1.4.06 | Identify render-blocking CSS | Minimized |
| 1.4.07 | Identify render-blocking JS | Minimized |
| 1.4.08 | Validate that main thread is not blocked by long JS tasks | < 200ms blocking |
| 1.4.09 | Identify duplicate JS requests | None |
| 1.4.10 | Identify duplicate CSS requests | None |
| 1.4.11 | Identify duplicate image requests | None |
| 1.4.12 | Identify third-party analytics calls | Count minimized |
| 1.4.13 | Identify third-party advertising calls | Count minimized |
| 1.4.14 | Identify API calls to same domain | Efficient usage |
| 1.4.15 | Identify API calls to external domains | Limited amount |
| 1.4.16 | Identify font files loaded | Optimized |
| 1.4.17 | Evaluate font file sizes | < 150 KB each |
| 1.4.18 | Detect WOFF2 usage | True |
| 1.4.19 | Detect unused fonts | None |
| 1.4.20 | Evaluate CSS file sizes | < 300 KB |
| 1.4.21 | Evaluate JS bundle sizes | < 1 MB total |
| 1.4.22 | Identify any single JS file > 2 MB | None |
| 1.4.23 | Confirm image formats (WebP/AVIF preferred) | Modern formats |
| 1.4.24 | Confirm lazy-loading on below-the-fold images | Enabled |
| 1.4.25 | Identify uncompressed images | None |
| 1.4.26 | Measure total page weight | < 3 MB |
| 1.4.27 | Measure time to first byte (TTFB) | < 500ms |
| 1.4.28 | Measure total page load time | < 4 seconds |
| 1.4.29 | Identify any non-cached static resources | All cached |
| 1.4.30 | Validate cache headers on static assets | Expires/Cache-Control present |
| 1.4.31 | Validate CDN usage for static assets | True |
| 1.4.32 | Identify HTTP/2 multiplexing | True |
| 1.4.33 | Identify HTTP/3 support | True |
| 1.4.34 | Detect requests to deprecated domains | None |
| 1.4.35 | Detect broken requests (4xx/5xx in HAR) | None |
| 1.4.36 | Validate that LCP resource is preloaded | Preload present |
| 1.4.37 | Measure load time of LCP resource | Fast (<1s) |
| 1.4.38 | Identify unused JS in coverage report | < 40% unused |
| 1.4.39 | Identify unused CSS in coverage report | < 40% unused |
| 1.4.40 | Compute total resource-load health composite score | >= 80% |
← 1.3 JavaScript Blocking & Hydration Suite1.5 Redirect Graph Flattening Suite →
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