Merchant Center Feed Checker: fix product feed errors before upload

Every product needs id, title, description, link, image_link, availability and price. Others depend on the product: brand for new products, gtin when the manufacturer assigned one, mpn when there is no GTIN, condition for used and refurbished items, and availability_date for pre-orders and backorders. In the US, the UK and a few other countries, variants also need item_group_id.

Write the number followed by the three-letter ISO 4217 currency code, such as 1299.00 INR, without a rupee sign or thousands separators. The price must match your product page and checkout. For India, include GST in the price. If you run a sale, keep the regular price in price and put the lower price in sale_price.

A GTIN has 8, 12, 13 or 14 digits, and its last digit is a check digit worked out from the others, so one mistyped digit makes the check fail. Numbers starting with 2, 02 or 04 are for in-store use, and those starting with 98, 99 or 05 are coupons. If a product has no GTIN, leave the field empty rather than making one up.

Google asks you to use your store name as the brand when you make a product yourself and are its only seller, and to add your own product code as the MPN. Do not write N/A, Generic or No brand. Only when a new product has no GTIN and no brand and MPN should you set identifier_exists to no.

It only makes changes that need no judgement: Google's column names, trimmed spaces, availability and condition values such as "In Stock" rewritten as in_stock, prices such as ₹1,299 rewritten as 1299.00 INR, spaces removed from GTINs and spaces in links encoded. It never shortens titles or changes IDs, GTINs or dates. Open it in a spreadsheet and check it before you upload it.