Web App Enhancement and Optimization

I need an expert developer to enhance and complete my large web application project. The ideal candidate will have:

- Extensive experience with [login to view URL]
- Strong skills in user interface design
- Expertise in backend integration
- Proven track record in performance optimization

Key areas of focus include:

- Improving user interface (Navigation)
- Enhancing backend integration (Database improvements)
- Optimizing performance

Additionally, I need to add or improve the following functionalities:

- User authentication (Two-factor authentication)
- Data visualization
- Smart Invoice process (should be connected with all Dept)
- Dashboards

Please provide examples of similar work done and any relevant credentials. Looking forward to your bids!