Does it work with sites that are not on Squarespace?

Yes. Any public website can be backed up the same way. Squarespace is what we know best and what the theme report is tuned for, but the pages, screenshots, and assets come from what the site serves.

The crawler reads a sitemap, follows links, renders pages in a real browser, and copies images, styles, and fonts. None of that depends on Squarespace. Sites on Wix, Showit, GoDaddy Website Builder, Webflow, WordPress, and plain HTML hosts all work.

Two things are Squarespace-specific:

• The theme report recognizes Squarespace templates, fonts, and integrations. On other platforms it lists what it can see, which is usually the fonts and colors, without a template name.
• The asset hosts we copy from include the Squarespace CDN by default. Other platforms' image hosts are added as we see them; if a site's images stay as links to the live site, tell us and we add the host.

Try the free backup on the homepage with any public page and look at the result before deciding.