How to Write Alt Text for a Whole Shopify Catalog With AI

Alt text is the easiest SEO and accessibility task to understand and the hardest to finish. One image takes thirty seconds. A catalog with 800 products and five images each is 4,000 of them, and that's why most stores have alt text on the first hundred images and nothing after.

AI changes the arithmetic. A model that can look at an image will describe it accurately in a second. The work shifts from writing to checking, which is a job you can actually get through.

Here are three ways to do it, from smallest to largest, and the rules that keep the output honest. For what good alt text is and why it matters, start with image SEO on Shopify.

What you're aiming for

Good alt text describes what's in the picture, for someone who can't see it.

• Good: "Navy wool crewneck sweater on a hanger, front view"
• Thin: "sweater"
• Stuffed: "buy navy wool sweater best mens sweater sale cheap wool crewneck"
• Wrong: "Navy cashmere sweater" (when it's wool)

Shopify's alt text guide allows up to 512 characters and recommends 125 or fewer. One clear sentence is plenty.

The last example above is the one AI makes possible at scale. A model describing an image can't know the fibre content from the photo. If it guesses, you've published a false claim 4,000 times. Hold onto that. It shapes every method below.

Method 1: Shopify's own suggestions (a few images)

Shopify's help center says the media editor might suggest alt text for images where it isn't already filled in, and that accepting a suggestion saves it to the file.

To add alt text to a product image by hand on desktop:

1. In your Shopify admin, go to Products and open the product.
2. Click a media item to open its preview.
3. Click Add alt text.
4. Enter the text, or use a suggestion if one is offered, and click Save alt text.

Use it for: new products as you add them, and your top sellers, where you want to write each one with care.

Its limit: it's one image at a time.

Method 2: A CSV and a vision-capable assistant (the whole catalog)

Shopify supports uploading alt text in a CSV file, and a product export has an Image Alt Text column next to each Image Src. That gives you a bulk route.

1. Export. In Products, export to CSV. Keep an untouched copy.

2. Start with a small batch. Take 20 products. Give the assistant the CSV rows along with the images. Assistants like Claude and ChatGPT can look at images you attach, and with tools that browse they may be able to open the image links in the file. If yours can't open the links, attach the images directly.

3. Prompt with rules:

For each image row in this Shopify export, write alt text in the Image Alt Text column.

Describe only what is visible in the image: the item, its colour, the angle or setting. Use the product Title for the product's name. One sentence, under 125 characters.

Do not state materials, sizes, or features unless they appear in the Title. Do not start with "image of" or "picture of." No keyword lists.

If two images of the same product look alike, make the alt text different by naming the view: front, back, side, detail, worn.

Leave rows that already have alt text unchanged. Leave every other column unchanged. If you couldn't see an image, write "NOT SEEN" instead of guessing.

4. Check it. Sort by the alt text column. Look for "NOT SEEN" rows, duplicates within a product, anything over 125 characters, and any claim about material or size. Then open ten images and compare them to their text.

5. Import. Import the CSV, choosing to overwrite products with matching handles. Review Shopify's preview before confirming. Spot-check three products in the admin.

6. Repeat in batches. A few hundred products at a time is easier to check than everything at once.

Use it for: a one-time catch-up on a catalog with years of missing alt text.

Its limit: it takes care. The assistant has to actually see each image. Alt text written from the product title alone, without looking, is how you get "blue shirt" on a photo of the size chart.

Method 3: An app built for it (ongoing)

If you add products every week, a one-time CSV pass will be out of date in a month. Apps that generate alt text for new images as they arrive solve the ongoing problem.

What to look for in one:

• It looks at the image, not just the product title.
• It shows you each suggestion before applying it. Nothing should publish without your say.
• It never overwrites alt text you wrote on purpose.
• It handles new products as they're added, not just a one-off run.

This is one of the things AgentReady does. It drafts alt text from the actual product images and shows you every suggestion before it's applied.

The rules, whichever method you use

Describe, don't claim. Colour, shape, angle, and setting are visible. Material, size, and origin are not. Those come from your product data.

Make each image different. Five images with identical alt text help nobody. Name the view.

Skip the obvious. No "image of." A screen reader already announces that it's an image.

Leave decorative images alone. A divider or background flourish doesn't need a description.

Review a sample, every time. Ten images per batch, compared by eye.

Don't overwrite good work. If someone wrote careful alt text on your hero products, keep it.

Where a connected assistant fits

If you've connected Claude or ChatGPT to your store through Shopify's official integration, you can ask about a product's images and have it update a product. Shopify's documentation lists images among the things the product update action covers, but it doesn't spell out alt text, and changes run one item at a time. For a catalog, the CSV route is more predictable. More on batch sizes in bulk editing products with AI.

What alt text does, and doesn't, do for AI search

Alt text matters first for accessibility. It's how a shopper using a screen reader knows what you're selling. It also helps image search.

For AI assistants, it's one more piece of text describing the product, and it should agree with everything else. If your title says "wool" and your alt text says "cashmere," that disagreement is a small reason for a model to trust the page less.

It isn't the main event. AI shopping assistants lean hardest on structured product data: name, price, availability, attributes. If that layer has gaps, alt text won't cover for it. The free AI readiness checker shows what AI assistants can read from your store, images included.

The short version

1. For a few images, use the media editor and Shopify's suggestions.
2. For a backlog, export to CSV and have a vision-capable assistant fill the Image Alt Text column, in batches.
3. For the ongoing stream, use an app that looks at the image and asks before applying.
4. Whatever the method: describe what's visible, never guess a material, and check a sample.

The same export, edit, and import pattern works for SEO titles and meta descriptions and for filling missing product data.