How to take the json of a https website and place it in a file

How to take the json of a https website and place it in a file

I am working on a project where I am at the point where I have a method
that opens the URL which is an https using the Client API. I now want to
take in the json of the website and store it in a file, then be able to
convert the data in that file into an object and be able to compare it
with different things. My question is how would I take the json of the
website and store it in a file, then convert it into an object?