Node Backend Development with Socket.io

I'm seeking a skilled Node.js backend developer with expertise in real-time applications and Socket.io, for a project with chat and graph features.

Requirements:
- Develop a robust backend in Node.js
- Implement real-time chat functionality
- Handle graph visualization using Socket.io

Ideal candidate should have:
- Proven experience in Node.js backend development
- Strong understanding of real-time applications
- Previous work with Socket.io
- Proficiency in data visualization, specifically graph data structures

Please note that this project requires an expert who can deliver efficient, scalable, and secure code.