Hello,
I've read your project description and I want to tell you that I've rich experience with Youtube API and I can build the Youtube to MP3/MP4 website as per your requirements. Lets have a quick chat to discuss this project.
We have extensive experience in Designing Websites, Building Portals, Mobile Application Development, Developing Complex Web Applications in all major platforms.
We have worked with several top companies and brands. If you want, I can share our portfolio with you as well.
Thanks,
Faizan