JSON
also: json payload, json object, json body, json file
A plain-text format for writing data that both people and programs can read, using labels and values like "name": "Ada".
JavaScript Object Notation: a text format built from key-value objects, arrays, strings, numbers, booleans and null. It's the default format for most API requests and responses, and for many config files. It's strict: double quotes only, no comments, no trailing commas.
A labeled packing list: item: lamp, quantity: 2, fragile: yes. A person can skim it, and a machine can check it line by line.
Most data your app sends and receives is JSON, and many config files are too. When an agent mentions "invalid JSON" or an "unexpected field", you'll be able to look at the data yourself.
The request fails because the body isn't valid JSON: there's a trailing comma after the last field. I'll fix the code that builds it.
Show me an example of the JSON this endpoint returns, with realistic values, so I can check the fields match what the app needs.
Thinking JSON is a programming language, or only for JavaScript. It's a data format, and nearly every language can read and write it.