The normal chargers that came with my cell phone and laptop can handle just about any electric current from 100 - 240 volts. The plug end might be different than what you have.
A converter (to me) means some heavy clunky thing that reduces or steps up voltage. My plug ends fit in many outlets but for some outlets a simple snap on adapter might be all you need. France and Japan have different voltages and different outlets. Look at the information printed on the charger that came with your various devices.
Worry more about the voltage for any device you have. If you have a single device - hair drier, electric massage thing or whatever - which is only 100 - 110 volts you can fry it in an outlet that takes 220 volts.
https://www.worldstandards.eu/electricity/plugs-and-sockets/
Google search will give you some "converters" but you may just need a simple, cheap, lightweight snap-on adapter.
[ Edit: Edited on 03-Dec-2019, 14:38 GMT by karazyal ]