Pro

Two passports? A family on different ones? Compare them.

Add each passport you or the people you travel with hold, and the visas that go with it. See which passport gets you in most easily, what everyone can enter together, and where anyone would need a visa.

Not travel advice. Each passport is checked on its own with the visas listed against it, from the same rules and sources as the checker. Dual nationals must usually enter and leave a country on the same passport, and some countries require their own citizens to use their passport there; check before you fly. Countries with no row in a list treat every passport the same way.