How do two websites compare, and what do they share?

Paste the two store addresses, for example your own store and a competitor, and press Compare. Both sites are checked at the same time. The result shows each site in its own column, with the items found on both in the shared lists and the items found on only one marked as such.

You can see the apps that put code on the storefront that visitors load: reviews, email and SMS sign-up, upsell, subscriptions, chat, search and page builders. Apps that work only in the Shopify admin, in checkout or through the API leave nothing a visitor’s browser receives, so no outside tool can list them.

Only what a visitor’s browser can see on one page, the home page, is compared. If a tool runs only on a server, loads on other pages only, or loads after a cookie choice or a scroll, it may not show up. So "only one site has it" means "it is visible on that site and not visible on the other", not that the other site does not use it.

Yes. Any public website can be compared. The platform, frameworks, hosting and CDN, analytics, advertising pixels, payments and chat widgets are compared for every site. The theme, app and store rows appear when at least one of the two is a Shopify store, and the store facts (currency, products) when both are.

Shopify stores publish their theme name and, for themes built from a base theme, the base theme name. The comparison matches the base theme, so a store that renamed its copy of a theme still counts as using that theme. Versions are shown next to each other so you can see whether they differ.

It is free. Nothing about the sites you compare is saved: no list of sites and no results. The last answer for a site is kept in memory for a short time so that repeated checks are quick, then forgotten. There is a limit on how many sites one visitor can check per hour.