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Image alt text via vision AI

Most SEO apps generate alt text by templating: ${product.title} - ${product.type}. That's not alt text. It's a placeholder.

RankEngine analyzes each image and writes descriptive alt text from what's actually in the photo.

Why this matters

  • Accessibility: screen readers read alt text aloud. Generic templated text is useless.
  • Image SEO: Google Images ranks pages with descriptive alt higher.
  • AI citation: ChatGPT and Perplexity often cite images by their alt text — better alt = better citation visibility.

How it works

  1. RankEngine fetches the image URL from Shopify.
  2. Sends it through RankEngine's image understanding pipeline.
  3. Receives 80-120 char descriptive alt text.
  4. Saves to Shopify as the image's alt attribute.
  5. Verifies the value persisted by re-fetching from Shopify.

Cost: ~$0.005 per image. Wallet-debited only on successful AI return — silent template fallback (rare) does NOT charge.

Where to use it

  • Per-product: Content tab → Images → click "Optimize all alt text" on any product card.
  • Bulk: On-Page → "Push to Score 100" → image_alt is one of the included branches.
  • Autopilot: Set a rule for "image_alt missing" → fixes new product images on a schedule.

Quality

  • 300-product test: 96% of generated alt text passed manual review on a kids-vitamins store.
  • Failure modes: images with no actual subject (gradient backgrounds, text overlays) get a fallback "${product.title} product image" — better than nothing but not vision-accurate.

What about images without alt?

Two states:

  • Missing alt (alt="" or alt attribute absent) — flagged as no_alt_text issue.
  • Partial alt (some images have alt, some don't) — flagged as partial_alt_text with a count.

Both are auto-fixable.

Tips

  • Verify before bulk. Run on 1-2 products first. If quality looks off (rare), edit your image style preset in Settings.
  • Don't overwrite good alt by default. The optimize-alt-text endpoint defaults to replaceExisting: false — images with non-empty alt are skipped. Phase 251 added a "Replace existing alt text" toggle in the per-product Optimize flow + a global Optimize button for whole-store sweeps. Flip the toggle if you want to overwrite (e.g. you've changed product type and want fresher descriptions).

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