Donating by PayPal is totally an option!
This is one of the preferred ways to donate to KiCad.
Follow the link from the kicad-pcb.org top right corner *Donate via CERN **.
Fill out your information and click on the DONATE button.
"All donations will be put to immediate use in developing KiCad. Any amount is welcome and will be gratefully received."
That button takes you to a page with:
There are also methods to donate tax efficiently.
To do this, follow the Support Us link on the top navigation link. This takes you to
a Giving to CERN - Support Us page, from which you can click on the Donate online link.
On the Giving to CERN Make a donation page, under the picture there is a link within the text * In certain cases, tax advantages can be claimed by your local tax authorities.* This takes you to a Giving to CERN - Tax efficient giving page. This page gives instructions for tax efficient giving from several countries.
For tax efficient giving from the US, donate to the 501(c)3 organization The King Baudouin Foundation United States (KBFUS) where, if giving by check, you can write "CERN & Society Foundation US Fund" in the memo field. More details by following just a few clicks.
(I didn't want to link directly to these pages just in case they changed over time.)