I donate to the against malaria foundation and another charity via the givewell foundation. At the end of the year they. send out an email with a signed pdf that you can declare for your taxes. I usually add 200-300 chf on top as “small donations” without providing any proof. GiveWell doesn’t hassle you either and doesn’t beg for money.
Sorry, it is https://ea-stiftung.org/ for Switzerland.