RESTful API & Custom Mail Builder Development

I'm seeking a skilled developer to create a RESTful API and a robust mail builder.

Key Requirements:
- Develop a RESTful API compatible with MacOS
- Support for both JSON and XML data formats
- Integrate a comprehensive mail builder for customizable transactional email templates
- User authentication required for the API

Ideal Skills and Experience:
- Proficiency in RESTful API development
- Experience with JSON and XML
- Familiarity with mail builder tools and customization

Please provide examples of similar work done.