It’s not downloadable software, but you might check out WordPress if you haven’t recently, it’s open source and free (though you do need to host it somewhere).
It used to have kind of a bad reputation for being a horrible hodgepodge of bad editing UI and random plugins that do things in wildly different ways, but the WordPress team has really stepped up their game in the last few years and it’s actually very nice now as long as you stay away from the commercial plugins. There’s almost always an open source plugin available for anything you’d want to do, but the out of box experience is plenty good for most pages you’d be likely to need.
WordPress has a very nice “block editor” enabled by default these days, which is essentially just their name for a WYSIWYG interface. Use drag and drop to design the pages, and then click a button to see it in a “code editor” that shows the HTML if you’d rather edit that way.
Anyhow, I know it’s not exactly what you asked for, but I thought I’d mention it since you did say you are open to something web based.
That depends who gets infected.
You or me infected by malware? No thanks!
Egon Mark infected by malware? Absolute hilarity!