You can use the AJAX plugin to communicate (get/read post/write) directly with web APIs.
You can use NW.js plugin to read and write from the local pc.
For online file hosting, there are a plethora of options out there, each with their own advantages, disadvantages, limitations and costs. Many of the paid services also have free tiers with limitations that might not be enough for your. You'll just have to find one that works for you.
webmasters.stackexchange.com/questions/26107/is-there-a-free-file-hosting-service-with-an-exposed-api-for-accessing-content
github.com/public-apis/public-apis
A common practice for games often use to share this kind of data is to convert it into a copyable text string, where people can stick it on a website or something like pastebin.
Obviously if have your own website/host you can set up your own system, which would be the proper way to do it.