PDF Submission and Approval System

I need a PDF upload and approval system designed for business clients. The system should be user-friendly and efficient, allowing businesses to submit documents for approval.

The ideal submission process includes:
- File size limit
- Multiple file uploads
- Drag and drop functionality

Ideal skills and experience include:
- Experience in developing document upload systems
- Familiarity with approval workflows
- Strong UI/UX design skills
- Ability to implement robust security measures

Please provide a portfolio showcasing similar projects.