There's the classic version of Boxcryptor that is not sold through the software as a service model, but just with a one time payment.
https://www.boxcryptor.com/en/classic
Differences with the new edition:
https://secomba.atlassian.net/wiki/display/DOC/Boxcryptor+vs.+Boxcryptor+Classic
It normally only allows you to sync, but you can also upload through the web interface. There is a program that allows allows you to load it like a folder and upload/download files without syncing. It costs $14/year but I think it's worth it.