Most online store projects do not wait on design or code. They wait on product data: the spreadsheet with half the prices missing, photos in three different sizes and variants nobody has listed yet. Having online store product data ready is the biggest factor a business controls in how quickly a store can launch, and it decides how well the store works once it is live. This checklist shows what to prepare before the build starts, whichever platform you end up on.
Why online store product data sets the pace
Every part of a store is driven by the catalog. Navigation comes from categories, filters come from attributes, shipping rates come from weights and dimensions, and Google's shopping listings come from identifiers and images. When the data is incomplete, developers either wait or fill the gaps with placeholders that someone has to find and fix later. In online shop development the data comes first for another reason too: the size and shape of the catalog show which platform will fit and which will fight you later.
A product data checklist to start from
Start with one spreadsheet, one row per sellable item, and these columns:
- SKU. A unique, stable code for every item and every variant. Agree on SKU naming rules before you start: no spaces, no characters that spreadsheets mangle, and never reused for a different product.
- Name. Clear and consistent, following the pattern customers search for, such as brand, product, model and the key attribute.
- Category. Where the product lives in the store's navigation, with one main category per product.
- Price. Retail price, any sale price and, if you sell to trade customers, their price lists.
- Stock. Quantity on hand and where it is held, or a note that stock comes from a supplier or an inventory system.
- Status. Active, discontinued or coming soon.
It sounds basic, but a list like this is where every online store development project we plan begins, because the catalog decides the rest. Most online store development services will ask for exactly this list, and it is where the gaps show up.
Product variants and product attributes
Product variants multiply quickly. A shirt in five sizes and eight colors is forty sellable items, each with its own SKU, stock level and sometimes its own photo. Decide which options are true variants, chosen by the customer and tracked in stock, and which are simply details that describe the product.
Product attributes are the details customers filter by: size, material, voltage, fit, compatibility. Keep them as separate fields rather than burying them in the description, with consistent values and units. "Stainless steel", "stainless" and "SS" become three different filter options if nobody cleans them up.
Identifiers, product photos and descriptions
- GTIN. The barcode number (a UPC in North America) that manufacturers assign to their products. Google Merchant Center strongly recommends a GTIN wherever one exists, alongside the brand and manufacturer part number; see its product data specification. If you make your own products, GTINs come from GS1 US. Never invent them.
- Product photos. The same background, framing and aspect ratio across the catalog, with file names that include the SKU. Google has announced a minimum size of 500 by 500 pixels for product images in Merchant Center, with enforcement from January 31, 2027, so keep large originals.
- Descriptions. Manufacturer text is a starting point, but it is the same text every other reseller uses. Write your own for the products that matter most, and keep specifications in attributes where shoppers can filter by them.
Shipping weight and dimensions, and tax
Carrier-calculated shipping rates need a shipping weight and dimensions for every product, and so does Google Merchant Center when carrier rates are used there. Measure the packed item, not the bare product. Oversized or fragile items may need their own shipping rules.
Sales tax settings depend on where your business has obligations, which products are taxable and whether you also sell through marketplaces. Your accountant should confirm the rules, and California's Department of Tax and Fee Administration publishes guidance for online sellers. Treat this as a planning note, not tax advice.
Getting the data into the store
WooCommerce, Magento and PrestaShop can all import products from CSV files, but each expects its own columns and format. The usual approach:
- Map your spreadsheet columns to the platform's import template.
- Run a product CSV import with twenty or so representative products, variants included, and check them in the store.
- Fix the mapping, then import the full catalog.
- Import images from URLs or a folder, matched by SKU.
If products already live in an ERP, a supplier feed or an inventory system, an automated sync may serve better than one-off imports; see ERP and PIM integration. And if the new store replaces an old one, keep a list of the old product URLs so each can be redirected to its new page.
Frequently asked questions: online store product data
Can I launch with part of the catalog?
Yes, and it is often sensible. Launching with your best sellers, complete and correct, beats launching everything with gaps. The remaining products can follow in batches through the same import template.
Do I need a GTIN for every product?
Only for products that have one. Handmade, custom or one-off goods may not, and Merchant Center lets you mark products that have no GTIN. Do not make up numbers or borrow another product's barcode.
Who should prepare the product data, us or the developer?
You know the products; the developer knows the platform. The most efficient split is usually that you supply names, prices, attributes and photos, while the developer defines the import template, cleans up formatting and runs the import itself.
Getting ready for a new store in Los Angeles? Our online store development service covers planning, product catalog setup, payment and shipping integration, testing, launch and training, on Magento, WooCommerce or PrestaShop. Request a quote and include a sample of your product spreadsheet; it tells us more about the project than any description.
