No, Shopify is not an open-source eCommerce platform. It is a hosted platform, meaning that the software and services used to power your eCommerce store are owned and managed by Shopify.
Shopify is a hosted, proprietary platform, but it does provide some developer tools that allow you to customize and extend the platform. For example, you can use Shopify's APIs and webhooks to integrate with other apps, customize store themes, and use pre-built apps and services to extend store functionality.
Shopify also has an app store where you can find plugins and extensions to add additional features and functionality to your store.
Ultimately, Shopify is a powerful eCommerce platform that is great for small businesses who don't have the resources to build their own eCommerce site from scratch. It offers lots of features and customization options, and its hosted nature makes it easy to set up and maintain.