The full source of the system taught in the InvetoTrack capstone, three codebases that talk to each other, not three separate demos.
The back office runs on Laravel with a role-based admin panel: products, stock levels, suppliers, sales, users and permissions. The REST API is the same one the mobile app uses, token-authenticated and versioned. The Flutter app is offline-first. A sale recorded with no signal is stored on the device and syncs itself when the connection comes back, which is the part most tutorials skip and every real shop needs.