JSONL file needs to be one JSON object per line. For eg:

{"id": "124", "company_name": "Stark Industries", "num_employees": 5215, "country": "US"}
{"id": "125", "company_name": "Future Technology", "num_employees": 1232, "country": "UK"}
{"id": "126", "company_name": "Random Corp.", "num_employees": 531, "country": "AU"}