A product compatibility checker tells a shopper whether a product works with the thing they already own: this ink cartridge with that printer, this belt with that mower, this battery with that e-bike. Merchants ask for one on the Shopify Community. This guide explains how a checker works and how to build one when what you sell is not car parts.

It is the same problem as vehicle fitment

Auto parts stores solved this years ago and call it fitment. A part fits some vehicles and not others, the shopper names their vehicle, and the store shows what fits. Replace "vehicle" with "printer" and nothing about the mechanism changes:

Each product has a list of the models it is compatible with.
The shopper picks their model from dropdowns that narrow each other: brand, then series, then model.
The store shows the products compatible with that model, and says yes or no on each product page.

What differs is the fields. A car is described by make, model and year. A printer is described by brand, series and model number. A mower by brand, model and deck size. A compatibility checker has to let you name the fields, because no fixed list covers every catalogue.

Field sets that work

You sell	The shopper owns a	Fields, in dropdown order
Ink and toner	printer	Brand, Series, Model
Appliance spares	appliance	Brand, Appliance type, Model number
Bike and e-bike parts	bike	Brand, Model, Year
Mower and garden parts	mower	Brand, Model, Deck size
Phone and tablet accessories	device	Brand, Model, Generation
Marine parts	engine	Brand, Model, Year

Two rules keep a field set usable. Put the field with the fewest options first, so each dropdown is short. And only add a field if it changes which products are compatible: a field that never changes the answer is one more thing for the shopper to get wrong.

Finding parts by model number

Shoppers of spares and consumables often arrive knowing only a model number printed on a label. They want to find parts by model number, not to browse a tree. A dropdown checker handles this if the model number is one of your fields and the earlier fields are short enough to get through quickly: brand first, then the model number. It is worth saying on the page where the number is found on the device, because that is the question that stops people.

The compatibility data

The data is a table with one row for each product and each model it is compatible with. Most merchants already have it in some form: a supplier's cross-reference sheet, a "compatible with" line in each product description, or a spreadsheet kept by whoever answers the support email.

One row per pairing. Product, then one column for each of your fields.
Ranges where they exist. A part compatible with model years 2019 to 2023 should be one row, not five.
Universal products marked as universal. A cleaning kit that works with everything should not need a row for every model.
Notes for the exceptions. "Not compatible with the Pro version" belongs beside the row it qualifies.

Keeping compatibility in product tags or in the description works until the catalogue grows. Tags are limited to 250 a product, and text in a description cannot be searched by model. See Shopify's product tag limit and fitment.

What Shopify gives you, and what it does not

Shopify has no compatibility feature. Its storefront filters can narrow a collection by a metafield, which covers "show me accessories for brand X" on a small catalogue. They do not give you dropdowns that narrow each other, a yes or no on the product page, or a model that is remembered as the shopper browses. The filter limits are in Shopify's collection filter limit for auto parts, and they apply to any catalogue, not only car parts.

Using ClearFitment for a non-vehicle catalogue

ClearFitment was built for vehicle fitment, and its fields are not fixed to vehicles. Fitment fields you define: vehicles, bikes, mowers, printers. You choose the field names, their order, and the word the storefront uses for what the shopper owns, so the picker and the fit badge speak about a printer or a bike, not a vehicle.

Start from the blank field set and add your fields, in the order the dropdowns should appear.
Set the noun. Vehicle, printer, bike, mower: it appears in the picker and on the fit badge.
Import your compatibility table as a CSV. You see what will be added, changed and skipped before anything is written.
Place the blocks in the theme editor: the picker, the fit badge and the compatibility table on product pages.

What it does not do: it does not look a model up from a serial number or a photo, it has no diagram or exploded-view parts lookup, and it does not check the cart at checkout. The shopper picks their model from the dropdowns.