Looking to build a Web app to service e-commerce accounts;
1) Ecommerce Inventory Management - handling multiple e-commerce accounts connected to carts (Shopify, WooCommerce) and marketplaces (Zalora, Lazada). Something like Orderhive
2) B2B Ordering - For the same accounts that also send items to retailers. Something like Handshake.
3) Tracking services - for the fulfilment.
4) Client portals
It's actually quite a massive system where integration is key between e-commerce carts, marketplaces, and the inventory system