I have been working on this Rust based JSON flattener (https://github.com/kindly/flatterer) to XLSX/CSV/SQLITE/PARQUET/POSTGRES for about 2 years. I finally made a WASM based one for CSV/XLSX which is really easy to play with. You can use it via a url (if the data has CORS headers), for example https://lite.flatterer.dev?url=https%3A%2F%2Fdummyjson.com%2....

The main difference with other converters/flatteners is that for one-to-many relationships (lists of objects in JSON) it produces a multi table output with keys to help join the tables together. Essentially produces a relational schema, along with some type information, of the JSON provided. For simple non-nested JSON it works too, but is a bit overkill.

Its all opensource and free, and I think that it will become more and more useful as JSON/Graphql APIs proliferate.