Shopify’s admin has a built-in bulk importer at Settings → Products → Import that accepts a CSV in its own specific column format. Getting that format right by hand - especially the rules around variant and image rows - is the most common way a bulk import goes wrong.

Choose the Shopify import CSV format above to build the file correctly automatically, whether you’re starting from another live store or a saved products.json. Upload the result on the Import screen, and Shopify will show a preview before committing anything.

Because this tool marks every imported product as an unpublished draft, you get a safety net: review titles, prices and images in the admin, fix anything that needs it, and publish only when you’re ready.

It’s worth doing a small trial import first, even with a well-formed file - five or ten products, checked over in Shopify’s own preview screen - before running a full catalog through, so any surprise shows up on a handful of products instead of thousands at once.