[marcotm]

You're welcome! For the chat model, it definitely helps to let it know that you want valid, parsable JSON (and nothing else). Otherwise it tends to get chatty. ;-) Depending on your use case, you might even ask it to fix the JSON if it's not parsable.

[number6]

I had the problem that it changed the layout of the JSON file: {"data": [...]} or {"products":[...]}.

In your first example, you told GPT what data structure you expected. I added this to my prompt, and now it produces the JSON Data consistently.