How would you give your vendors access to their share of business on Shopify?

When a Shopify/Magento/Opencart shop hosts multiple brands, it becomes necessary to provide each brand owner with a console to monitor and preview sales pertaining to his/her brand. To make this possible for our client, Kill The 8, we built a client portal where each brand owner has his/her unique log-in credentials to view the details of only his/her online store. We used the API of the e-commerce platform (that we created the store on) to fetch product, customer, order and inventory details from the brands’ online shops into the client portal.