MITM and security

[followingsun]

Hi all, I don't know if it exists or it is an upcoming functionality but I would like to know if I can cypher the data I send/receive by wifi.
For example, if I connect to a free-wifi spot, can I be sure nobody is monitoring the data or do even a MITM attack?

Is VPN the only solution available? -besides not connect to a free-wifi spot, obviously-
I don't want to pay for a VPN solution, really.

Thanks!