Cross-Platform Collaboration Tool Development

I'm seeking an experienced software and web developer to create a user collaboration platform. The platform should support real-time chat, file sharing, and collaborative editing.

Key Requirements:
- Functionality: Real-time chat, file sharing, collaborative editing
- Platforms: Desktop, mobile, and web-based access

Ideal Skills and Experience:
- Proficiency in web and mobile app development
- Experience with real-time communication technologies
- Strong background in file sharing and collaborative tools
- UI/UX design skills for a seamless user experience across platforms

Looking for a developer who can create a robust, user-friendly collaboration tool.