My first employer used Excel "in production": A C# app would read numbers from a shared network drive, feed them into a timeseries database, and the real-time p

My first employer used Excel "in production": A C# app would read numbers from a shared network drive, feed them into a timeseries database, and the real-time part of the system would be reloaded. Eventually a web-interface was put in place instead of the Excel sheet that provided for faster input validation.