What kind of API are you asking for? API is a very generic term, it may reach from C-programming APIs to REST v2 APIs, so some more explanation might be helpful.
Regarding PowerCenter, there are several APIs available out of the box; you can use command-line utilities, you can use SOAP web services, you can use Java or C code to control and monitor PowerCenter jobs.
Thanks for the update.
Currently customer is using the Dell Boomi platform to convert files as well as make API calls and they trying to see if Informatica could replace that platform.
My apologies for that, but I simply don't know the Dell Boomii platform, so I can't understand from your question whether Boomii is a virtualisation platform or whatever. In other words: what do they use Dell Boomii for? What kind of "replacement" is meant here?
And what kind of API calls do we talk about?
As Nico stated, the question is rather vague and can be quite broad in scope. I wouldn't think the forum is an appropriate place to look for an answer for this. Please check with your Infa sales rep and that person should be happy to direct you to the right resources.