Utility/Tools Cross-Platform App Development

I'm seeking a skilled developer to create a utility/tools application for both Android and iOS. The application should be centered around user authentication, push notifications, and subscription purchase and management.

Ideal Skills and Experience:
- Proficient in cross-platform mobile app development, specifically with Android and iOS
- Experience in integrating user authentication systems
- Knowledge in implementing push notifications
- Expertise in developing subscription-based applications
- Excellent understanding of utility/tools app development
- Strong portfolio of similar applications