AVIF or WebP served on a meaningful share of raster images
Modern image formats give crawlers more visual fidelity per byte ingested.
What this signal tests
We inspect the Content-Type response header and file extensions across the images on your page and count how many are served as AVIF (image/avif) or WebP (image/webp) rather than older formats like JPEG or PNG. At least 30 percent of raster images should use one of the modern formats.
Why it matters for your visibility in AI
AVIF and WebP deliver the same visual quality as JPEG at roughly half the file size, sometimes less. For AI crawlers and multimodal models ingesting your site, that means they can pull more images per unit of bandwidth and per unit of time before hitting their per-page budget. Sites still serving JPEG everywhere effectively get fewer images ingested by AI pipelines than equivalent sites on modern formats. This matters most for image-heavy sites: e-commerce catalogs, photo journalism, design portfolios, recipe sites. A retailer serving WebP product photos gets a larger fraction of their catalog into AI shopping graphs than a retailer who stayed on JPEG. The difference is invisible to humans (the images look identical) but very real in machine ingestion volume.
Pass criteria at a glance
| Criterion | Passes when |
|---|---|
| >=30% of raster images served as AVIF or WebP. |
How we test it
Our scanner samples the images referenced on the page, sends a HEAD or GET request to each, and reads the Content-Type response header plus the file extension. We count what fraction of raster images are served as image/avif or image/webp and report whether that fraction reaches 30 percent.
Show technical detection method
Inspect Content-Type and file extensions across image requests; count fraction image/avif or image/webp.
If your site fails: how to fix it
- Convert your image library to AVIF or WebP at build time. Use Squoosh (browser), cwebp/avifenc (command line), or ImageMagick's WebP/AVIF support. Most CDNs (Cloudflare Images, Cloudinary, ImageKit) auto-convert on the fly.
- Serve modern formats with content negotiation: configure your CDN to send WebP/AVIF to clients that advertise Accept: image/avif,image/webp, and fall back to JPEG/PNG for older clients.
- Or use <picture> with explicit type sources: <picture><source type="image/avif" srcset="image.avif"><source type="image/webp" srcset="image.webp"><img src="image.jpg"></picture>. This gives crawlers a clear menu of formats to pick from.
- Set quality levels carefully. AVIF at quality 50 typically matches JPEG quality 80. WebP at quality 75 usually matches JPEG quality 85. Tune per use case (photography needs higher quality than UI screenshots).
- If you use WordPress, plugins like ShortPixel, Smush, or Optimole convert and serve modern formats automatically. For Shopify, the built-in image transformation already supports WebP via URL parameters.
Quick facts
| Maturity | ESTABLISHED |
|---|---|
| Weight | low |
| Category | Multimodal |
Primary sources
Related signals
Frequently asked questions
Should I serve AVIF or WebP if I can only pick one?
WebP has wider compatibility and is generally easier to author. AVIF compresses better but encoding is slower and tooling is younger. For most sites WebP is the practical choice. If your CDN supports both via content negotiation, ship both and let the client choose.
What about JPEG XL? Is that worth adopting?
JPEG XL is technically excellent but browser support is patchy (Safari only as of 2026). It is not yet worth the operational cost for most sites. Revisit when Chrome and Firefox ship it. AVIF or WebP today, JPEG XL maybe next year.
Will switching formats hurt my image quality?
Not if you tune the encoder right. Run side-by-side comparisons at several quality levels. WebP at quality 80 typically looks indistinguishable from JPEG at quality 90 while being half the size. Run a perceptual quality test (Butteraugli, SSIM) before committing to a quality preset.
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