If they're going to put it in Excel, just use their formats[1], [2]. [1]: https://news.ycombinator.com/item?id=15476951 https://news.ycombinator.com/item?id=15

If they're going to put it in Excel, just use their formats[1], [2]. [1]: https://news.ycombinator.com/item?id=15476951 https://news.ycombinator.com/item?id=15476951 [2]: https://www.google.com/search?q=simple+xlsx+writer https://www.google.com/search?q=simple+xlsx+writer If it's something you're streaming, using a binary messaging format is always faster/better. I tend to use Kx's format since a lot of my messages go from to their systems, but Erlang's binary term format is good too -- even if you're not using Erlang.