Tools to create a nice wiki?

Hi everyone! I'm currently looking for a tool to create a nice wiki for our internal team of volunteers. I would like to create a nice onboarding process, some separate folders for our differents teams, ... As a non-profit organization, we don't have a lot of money to spend for a tool like this. I already know about Coda and Notion but their free plan start to become quite limited for us. If you have any recommandations, let me know! Thanks a lot