Is Spanbox actually free, or is it one of those 'free' trials that nag you to pay?

It's genuinely free, not a trial. You can connect any 3 apps (your pick of the 60+) and use them for as long as you like, with no account and no sign-up, they don't even ask for an email. Nothing expires and there's no nag screen counting down. The paid Pro plan only unlocks MORE than 3 apps plus some deeper inbox features; if three covers you, you never pay a cent. I've had the free version running for months without a single 'upgrade now' popup.

The 'no account needed' part is the tell, there's nothing to trial because there's no signup. You download it, add up to 3 apps, done. Pro is opt-in when you want unlimited apps.

Free is capped at 3 apps, not 3 days. Big difference from the usual trial trap. If you only live in WhatsApp, Slack and Gmail, free is the whole product for you.

Worth adding: because there's no cloud account, 'free' here really means free, they're not monetising your data on the backend either. Local-first means there's no server holding your stuff.