JSON to Excel; multiple tables; c#/.NET component

We have a bunch of complex JSON data. All in individual text files. We want you to build a tool to convert them into Excel files with multiple tables/sheets. The conversion tool will eventually need to be available to our C#/.NET application (local, not web-based). We don't have a schema, so part of the project is to get the data laid out in a sensible way so that we can work together on developing the destination schema. Please let me know in as much detail as possible what your approach to this will be.