Cross-Platform Utility App Development

I'm looking for an experienced app developer to create a cross-platform utility app. The app should include:

- User authentication
- Data synchronization
- Push notifications

Ideal Skills and Experience:
- Expertise in cross-platform app development
- Strong background in implementing secure user authentication
- Experience with data synchronization techniques
- Familiarity with push notification services

Please share your portfolio and relevant experience. Looking forward to your bids!