Hello
I have done similar work in the past, calling APIs from Node.JS, parsing documents, and saving results to a file.
After I have a better idea of what your initial input file is like, I can hand you the program back within 12 hours (I'd say 3 hours max after seeing an example input file, really).
That would be my first experience with through Freelancer, and would allow me to get my first rating.
I currently work for a company where I am the leader full stack developer/engineer, and I run a website pulling info from our own Node.JS server.
I'd be happy to provide more information if you like.
Thank you for reading my "proposal".
Regards