Node.js API Update Specialist

I need a Node.js developer to modify existing APIs. The modifications include:

Changing response data format to JSON.
Updating authentication methods.
Enhancing performance.

Ideal skills and experience:
- Proficiency in Node.js
- Strong understanding of API development and modification
- Experience with JSON and data format changes
- Knowledge of authentication methods and security
- Performance optimization skills

Please provide your relevant experience and approach.