I read that SSL is not natively supported, will links made via joturl (including custom domains if we add them) support https (SSL) with no further action or cost?

Actually, a shared SSL certificate (like provided by other players) would not allow you to add your own custom SSL certificate for each custom domain, which is definitely an added value provided by JotUrl :)

But the good news is that you don't need to purchase a SSL certificate for your branded domain in JotUrl.

In fact you can also use Letsencrypt.org, where you can get SSL certificates for free, which is supported within JotUrl.

Go to your account (top right corner of your dashboard) -> Settings -> SSL Certificates -> then just click on the "Get a free certificate" button to run the automatic wizard and get a free SSL certificate.