@HistoPol Ah, I am so sorry, yes, my answer applied to the other tools that use Mastodon's API.
For the posting history, yes, that tool does require uploading the file to my server for the time being (this is only to be able to unzip the archive), but I should be able to remove that requirement, apparently there is a library that lets you do that in the browser.
As an alternative in the meantime I'd recommend https://s427.github.io/MARL/dist/index.html (it was from its author I learned about this library, which it uses).
Sorry about the confusion!