CSV is the least glamorous and most durable data format there is - rows of values separated by commas, readable by every spreadsheet and database ever written. Its subtleties are all about quoting: a value containing a comma has to be wrapped, and a quote inside that has to be doubled.
Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a CSV file above and choose afterwards.