Save your tiddlers to remoteStorage!
Works anywhere, just grab the plugin on $:/plugins/fiatjaf/remoteStorage, save, reload, optionally change your preferences on $:/plugins/fiatjaf/remoteStorage/config and you'll be good to go.
Your tiddlers will be saved on /public/tiddlers/<chosen-namespace>/.
<chosen-namespace>defaults to"main".
If you're just starting a new TiddlyWiki you don't have to bother installing anything, just visit https://tiddly.alhur.es/ and start writing. Changes will be saved locally, but you can login anytime to a remoteStorage account and your tiddlers will be saved automatically there.