Cross-Platform Mobile Web App Development

I'm looking for an experienced developer to create a mobile web app optimized for both iOS and Android platforms. The app will include essential features like user authentication and push notifications.

Key Requirements:
- inventory
- invoice
- User authentication to ensure secure access.
- Push notifications to engage users.
- Responsive design for seamless experience on both platforms.

Ideal Skills and Experience:
- Proven experience in developing mobile web apps.
- Strong expertise in user authentication and push notifications.
- Proficient in responsive web design for iOS and Android.

Please provide a portfolio of similar projects.