Looking for a software that communicates with an existing API

Hello,

I work with an SaaS company that works with rest API. Our clients are able to submit forms which can then be sent to them as PDF files from a template. I was wondering if it would be possible to send chunks of text and other data from our API to a software so that it could be easily customized.
Basically something like Powerpoint where you can easily move objects around, but with an API integration.

I know it’s a bit of a stretch and extremely specific, but if anyone has any ideas it would be greatly appreciated!