Yes. It also provides a really nice UI for building our www site which we like to rev frequently. Webflow is the bomb if you are familiar with HTML and CSS. Super clean HTML, total control over all the css attributes, drag and drop builder.

Is it a completely hosted service? It looks cool, but I'd be reluctant to use it if it's a subscription to an online tool where I have to pay forever. Is there a standalone version of that editor?

It is hosted, but you can use it free forever if you have Netlify in front of it and use your free sitename.webflow.io URL as your origin server. You can also export your site as static html if you want.