Alt text is the most overlooked SEO win on Shopify. It does four jobs at once: it tells search engines what an image shows, powers Google Images traffic, makes your store accessible to screen readers, and now feeds the AI models that "look" at product photos before they describe or recommend them. On most stores it sits empty, which means every product image is an unindexed asset doing nothing for you.

What alt text actually is on Shopify

Alt text is the written description attached to an image so software can understand it when the picture can't be seen — by a blind shopper using a screen reader, by a crawler indexing Google Images, or by a slow connection where the image fails to load and the text shows in its place. In your admin you set it per image under Products → [product] → Media: hover the image, click the pencil or "Add alt text" control, and type the description. Collection images, blog post images, and files uploaded under Content → Files each have their own alt field too.

Shopify renders that field into the storefront markup as the image alt attribute. That is the exact string Google, Bing, and the AI crawlers read. There is no separate "SEO alt" and "accessibility alt" — it is one field doing both jobs, which is why the wording has to serve a human listener and a machine reader at the same time.

What good alt text looks like

Describe the image specifically and naturally: what it is, its key attributes, and the context or angle. "Women's merino wool running sock, charcoal grey, ankle height, side view" beats "sock" and beats a keyword-stuffed string like "sock socks running sock buy socks online best socks." The first version tells a screen-reader user exactly what they are looking at and gives Google Images a precise thing to rank. The stuffed version reads as spam to both.

A few rules that hold up in practice on Shopify:

  • Don't start with "image of" or "photo of." Screen readers already announce that it is an image, so those words are wasted and slightly annoying to listen to.
  • Keep it under about 125 characters. Some screen readers cut off around that length, and past it you are usually padding.
  • Describe what the eye sees, not what you wish the page ranked for. If the photo is a grey sock, "grey merino running sock" is honest; "best affordable athletic compression socks 2026" is not in the photo and does not belong in alt text.
  • Every image on a product should get distinct alt text. The front, the sole, the packaging, and the lifestyle shot are four different images and deserve four different descriptions.

A repeatable pattern that scales

For product images, a reliable template is the product's core noun plus its most search-relevant attribute plus the variant or angle: {product title}, {key attribute}, {variant or angle}. So a product called "Trail Runner Sock" photographed in three colors and two angles becomes six unique lines like "Trail Runner sock, charcoal, side profile" and "Trail Runner sock, charcoal, sole tread detail."

The pattern works because it forces the two things Google Images rewards — a clear subject and a differentiator — without inviting you to keyword-stuff. It also keeps a large catalog consistent, so nobody on your team has to guess the house style image by image.

The mistakes we see most often

  • Leaving alt empty. This is the default for almost every image uploaded to Shopify, and it is the single biggest cause of zero Google Images traffic on otherwise decent stores.
  • Copying the product title verbatim onto every image. Ten images with the identical alt string tell Google nothing about which image is the sole, which is the packaging, and which is the on-model shot. Distinct descriptions win.
  • Keyword stuffing. Cramming the same phrase in three times, or listing every color you sell, reads as manipulation and can hurt more than blank alt would.
  • Describing decorative images. Not every image needs alt text. A purely decorative divider, background texture, or spacer image should get empty alt (alt="") so screen readers skip it rather than reading out noise. In practice on Shopify this mostly applies to theme and section images, not product photos — product photos are always meaningful and always deserve real alt text.
  • Writing alt text that contradicts the image. If the alt says "blue" and the photo is red because someone swapped the variant, you have created a small trust problem for both accessibility and search. Alt text has to track the actual image.

How alt text feeds Google Images and AI

Google Images is a real acquisition channel for product stores, and alt text is one of the strongest signals it uses to decide what an image is and which queries it should surface for. Pair good alt text with a descriptive image file name, image dimensions that aren't wildly oversized, and a fast-loading page, and you give Google everything it needs to rank the picture. Our fuller take on the surrounding signals lives in the image SEO for Shopify guide.

The newer reason alt text matters is AI. Answer engines and shopping assistants increasingly interpret product photos, and where they can't or don't run vision on every image, they lean on the alt text you wrote. A ChatGPT or Perplexity answer that recommends a product is more likely to describe it correctly when the underlying image carried an accurate description. That makes alt text part of answer engine optimization and the broader AI search optimization picture, not just classic image search. If you care about being described accurately by AI, alt text is one of the cheapest ways to steer it.

A fast way to check your coverage

You can spot-check any product page by opening it on the storefront, right-clicking an image, and using your browser's inspect tool to read the alt attribute — empty quotes mean the field is blank. For a store-wide read, crawl your site with any SEO crawler and sort images by "missing alt." What you'll usually find is that a handful of hero and collection images have alt (someone did them by hand) and the long tail of product images — the ones that actually drive Google Images traffic — are blank.

Doing it across a whole catalog

Writing alt text for a large catalog by hand never finishes. A store with 2,000 products and five images each is 10,000 descriptions, and by the time you reach the end you've added 300 more products. This is the classic job that only gets done with automation. The right approach isn't a template that pastes the product title onto every image — that reproduces the "copied title" mistake at scale — but genuine per-image description generated from the actual photo. It's also worth handling alongside the rest of your on-page work in a single pass; see how it fits the wider product page SEO and the 2026 Shopify SEO checklist, and where an app fits in the Shopify SEO tools landscape.

RankEngine uses vision AI to look at each product image, generate an accurate, specific description from what's actually in the frame, and write it back to Shopify with the change verified against your live store — then tracks coverage so you can see "18 / 18 images have alt text" at a glance instead of guessing.