Cross-Platform Social Networking App Development

I'm looking for an experienced app developer to create a social networking application that runs on web, desktop, and mobile platforms (iOS, Android, and Windows).

The app should facilitate real-time interactions among users, including features such as:
- User profiles
- News feeds
- Messaging
- Friend connections
- Content sharing (photos, videos, articles)

Ideal skills and experience:
- Proficiency in cross-platform app development
- Experience with social networking app features
- Strong UI/UX design skills
- Knowledge of backend technologies to support real-time data processing
- Familiarity with security protocols to protect user data

Please provide a portfolio showcasing similar projects.