FinTech App API Integration Expert

I'm seeking a seasoned professional with a strong focus on API Integration, specifically for a FinTech application I'm developing.

Key Areas of Focus:
- Expert level understanding and experience in API Integration.
- Full proficiency in React.js for frontend development.
- Extensive knowledge and application experience with Node.js for backend development.

The ideal candidate will have a robust portfolio showcasing:
- Prior experience in FinTech app development.
- Successful API Integrations in past projects.
- Innovative and efficient use of React.js and Node.js.

Please provide relevant examples from your past projects.