Hey there,
If you know the structure of e.g. JSON Body then it is fairly simple to use a “template” body JSON object in your workflow and to update it using JSON Transformer node.
You can save JSON file using JSON Writer.
The JSON objects you create / modify you can use in GET / POST Request nodes etc.
Minimal example of JSON Transformer and reader in attached workflow:
Overview:
Workflow
JSON.knwf (76.7 KB)