Cross-Platform Task Management App Development

I'm seeking an experienced app developer to create a utility task management app for both iOS and Android platforms.

Essential requirements:
- Build a user-friendly interface for efficient task management
- Ensure seamless performance across both platforms
- Implement secure file storage for user data
- Integrate a reliable reminder system

Ideal skills and experience:
- Proven expertise in developing cross-platform mobile apps
- Strong background in UI/UX design
- Familiarity with secure data storage solutions
- Prior experience with task management app functionalities

Please provide your portfolio and relevant project experience.