Capturing Form Data as JSON

Hi Everyone:

I'm working on a project and I would like to be able to bridge the gap between a Squarespace site and a custom app I am developing. In the simplest terms, I want to be able to capture form data from a Squarespace form and render it as JSON to use in my custom app.

I've looked into options like Zapier and n8n.io, but I don't have the budget to use third party services, nor do I want to rely on them to parse my data. 

Does anyone know of any way to capture form data from a Squarespace form and convert it to JSON to use in a custom app for free?

Any advice is greatly appreciated.

Thank you,

Daniel