Haven't used them personally, but at least Plus codes are open source and have a permissive license. what3words had huge marketing campaigns (TV) in my country

Haven't used them personally, but at least Plus codes are open source and have a permissive license. what3words had huge marketing campaigns (TV) in my country, but when we (logistics software devs) looked into using it ourselves a few years ago, it was rather complicated (licensing) and expensive. In the end we decided against any "human geo-encoding" system and provide other solutions that make transmitting geo locations between humans obsolete.