Zamzar’s one of those free online resources I’ve used for a very long time (at least 15 years). Good chance you already know/use it. I’m posting it now since I just used it again, and realized I haven’t mentioned it since that one post many years ago now lurking in the depths of the archive dungeon. So here we are.
Zamzar does file conversions. Between just about every file format that matters imaginable. No software to download, everything’s done through its site. Document, image, audio, video files… check check check check. It even does ebook format conversions!
I myself find it really handy for turning PDFs into editable text or Word files, and for seamlessly converting the occasional EPUB ebook to the MOBI format my Kindle likes.