Spanbox vs Rambox/Franz/Ferdium, what actually makes it different?

They're in the same family (dock all your web apps in one shell), so the differences are in the details. Spanbox leans hard on local-first privacy (no account, nothing routed through a server, credentials never stored) and on a genuine unified inbox plus a ⌘K command bar to jump anywhere, rather than just being a tabbed container. Multiple accounts of the same app in isolated sessions is first-class, not a hack. Franz historically pushed a paid account/sync model; Ferdium is the community fork and solid but more DIY. If you want the tidy, private, no-signup version with a real cross-app inbox, that's the Spanbox angle.

Franz wanted an account and nudged you to pay to add services; Ferdium fixed that but you're assembling it yourself. Spanbox feels more finished out of the box, and the unified inbox + command bar is a step past 'just tabs'.