Build a Web-Based Tool for Amazon FBA Box Content Workflow

I need a web-based tool for managing FBA shipment box content.

Key requirements:
- Import Amazon-generated box content files.
- Allow warehouse staff to input box-wise information.
- Function offline after initial upload, due to variable connectivity.
- Export file in Amazon's format for upload to Seller Central.
- User access control for admin and regular users.
- Additional functionalities: data validation and error reporting.

Ideal skills and experience:
- Web development expertise
- Experience with data import/export tools
- Familiarity with Amazon Seller Central
- Strong background in implementing user access controls and error handling