Out Of My Depth!

Hey Everyone!

Relative API beginner here!
For years I have been working with http POST systems where data could be transmitted as parameters directly or as JSON. I have even created systems utilising postman to post batch files of collected data to CRMs utilising Postman.

More recently I have been working with systems requiring the live transfer of form data, securely from web page to various servers on behalf of my clients.
the system I utilise normally does a great job of integrating with both JSON or XML based data transfer, when we have found an anomaly.

The system strips out underscores in field names, meaning this client I cannot pass the data through as the field is not correct.

Therefore, I am looking for a way to pass the data from the form, capture it, format the fields & then post on to the client.

I am able in postman to build the part that posts the data on, my head says I need to script PHP to capture the inbound data. But then I hit a bit of a loss.

Can someone assist or point me in the right direction as to how I can understand/learn how I can join the dots.

My guess is that I will need to deploy the code from postman to a server to generate an end point. Do I need a specific server or would the cloud version I use as a hosting solution suffice?

As I say… out of my depth!

Any help would be greatly appreciated!

Thanks in advance!