Hi,
APIs is thing i like to build :)
I offer to add API on you platform, with PHP Frameworks like SLIM, Laravel. (Works on most hostings)
It would be simple HTTP/Restfull based API, with HTTP/HTTPS + API key authentication. compatible with variety of range other platforms.
Price I bid is high because i dont know how complex data needs to be updated, please contact with me so I/you can give more details.
+ I will create good api documentation.
+ I can work on you server, so you can see everything i work on, and test it.