Note I am referring to a local proxy, listening on the loopback device and under the control of the user, not one listening on a network interface connected to the internet and certainly not one operated by a third party as a "service".
shameless plug: see autossl.so[1]. it is not a proxy per se, but an LD_PRELOAD-able lib which upgrades plain socket connections to TLS for applicaitions which does not support TLS themself (or using too old SSL versions).
Note I am referring to a local proxy, listening on the loopback device and under the control of the user, not one listening on a network interface connected to the internet and certainly not one operated by a third party as a "service".
https://www.stunnel.org
Good luck.