Alt text for a whole Shopify catalogue: where to start

Three hundred products with three photos each means nine hundred alt texts to write. An earlier article on this blog explains what good alt text looks like for a single image. This one answers the next question, the one you face in front of an entire catalogue: where to start, and how to finish without spending your evenings on it or sliding into keyword stuffing.

Start by looking at where you stand

In the Shopify admin, open a product, click a photo, then "Alt text". That is where the text is read and edited, one photo at a time. Shopify recommends 125 characters or fewer, and the field accepts up to 512.

The 125 figure is a guide for brevity, not a limit of the field. It is a good guide, because a product photo is well described in one sentence, and a short sentence is easier to follow with a screen reader.

Do this check on five of your best sellers. If you find empty fields, file names like IMG_4471, or the same text copied onto every photo of a product, you already know what needs doing, and you can assume the rest of the catalogue looks like that sample.

The order that pays off first

You do not need to do everything at once. Four steps, in this order:

1. The main photo of your best sellers. It is the one shown on collection pages and in image results.
2. The other photos of those same products: back, details, product worn.
3. The rest of the catalogue, one collection at a time.
4. Purely decorative images (banner, background pattern): an empty text, alt="", is the right answer under the W3C accessibility guidance. A product photo is almost never decorative.

One template per photo type

The slow part is not writing, it is working out what to write. One template per photo type settles that once and for all:

Each text describes what you see in that particular photo. The product name can appear when it reads naturally, and no more than that.

Three traps specific to catalogues

The same text on every photo of a product. It is the most tempting shortcut. Someone listening to the page with a screen reader hears the same sentence five times and learns nothing more about the product. Two different angles deserve two different sentences.

"Photo of" and "image of". The screen reader already announces that it is an image. Start directly with what it shows.

Stacked keywords. Google says it plainly in its image guidance: filling the alt attribute with keywords hurts the experience and may be treated as spam. An honest description already contains the right words.

What PixelUnik does at this scale

Writing nine hundred sentences by hand is still possible with the templates above. If time is short, this is exactly the work PixelUnik was built for.

• The AI looks at the photo itself. It also receives the product title, the variant linked to the photo, and the texts already written for the product's other photos, so it does not repeat them.
• One complete sentence, 125 characters at most. If the text runs over, the app asks once for a shorter version; if that still does not fit, it rejects the result and refunds the credit. You never get a sentence cut off halfway.
• In your language. The text follows your storefront language, or the one you pick among seven languages, including English and French. Four tones to choose from: professional, friendly, luxury, technical.
• You stay in control. In the SEO Editor, the suggestion fills the field, you edit it if needed, and nothing is written to your store until you click "Save alt". If you do not like it, "Suggest another" asks for one that is genuinely different.
• The photos to fix are already sorted. Filters show photos with no text and those whose text is too weak to help ("image", "photo 2", and so on).
• New photos take care of themselves (Growth plan). In automatic mode, every photo added to a product is optimised, then gets its alt text, without overwriting a text that is already useful.
• The text stays yours. It is written to Shopify's native field, not a script, so it stays in place if you uninstall the app. And when PixelUnik optimises or renames a photo, the existing alt text is kept.

Each generated text costs one credit. On install, 30 trial credits let you cover your best sellers before deciding anything. After that, Starter (100 credits a month) and Pro (500) handle photos one at a time. Processing every photo with missing or weak text in a single batch is reserved for the Growth plan, which includes 1,500 credits a month: nine hundred photos fit in a single month. In automatic mode, a new photo costs two credits: one for the optimisation, one for the text.

The batch writes straight to your store, without photo by photo review, so check a sample by hand before running it. And if you deliberately left a photo's text empty to mark it as decorative, note that the batch treats it as a photo to describe.

Tonight's step

Open your best seller, click each of its photos, and read their alt text. If one is empty or carries a file name, write its sentence with the template above. Two minutes, and the photo your customers see most often is sorted.