Popular across PL, Blinkee offers 83 electric mopeds throughout Kraków during the warmer months. Use their app to find one, 'unlock' it, drive it around town and drop it off wherever you like; each moped has one helmet stored in its trunk (but can seat two people). A fun way to explore the city, there's nothing more gratifying than weaving through Kraków's typical traffic gridlock. It's also ecological, which is no small thing in a city with a serious smog problem. Believe it or not, if you're over 24 all you need to drive one is a valid ID, but if you're 24 or under you need a valid driver's licence that's recognised in PL (as such, Americans, Australians, Chinese and others from countries that did not ratify the Vienna Convention on Road Traffic cannot drive on their home licence, but rather need an International Driver's Licence).
If the license is an issue, you can always rent one of their e-scooters - of which there are currently 169 across Kraków - with the same app, in the same way. The advantages of an e-scooter are that you don't have to stick to the roads, or find a legit parking space to end your ride, but note that the range is more limited and does not include some tourist areas like Podgórze.