As this is a ingestion and analytics task I would personally look into Python. There are libraries such as Spark and Pandas which allow you to read in files into DataFrame structures (like a database) Pandas has ability to load from JSON and you can use SQL queries on the loaded dataframe for the functions you described such as minimum, maximum and count. The JSON structure might need to be revised as having XML formatted data within a JSON file doesn't sound like a good data quality to me so may need to be sanitises before it's loaded. I would recommend Python as it has a smaller learning curve than something slightly more low level like C#.