Web-Based User Data Import App

I need a web-based application built in base44. This app will allow administrators to import user data from Excel sheets.

Requirements:
- Import excel data containing user properties
- Validate by checking for duplicates

Ideal skills and experience:
- Proficiency in base44 development
- Experience with web application development
- Strong data handling and validation skills
- Familiarity with Excel data import functionalities

Please provide a portfolio showcasing similar projects.