Smart HTTPS is described as 'automatically changes HTTP protocols to the secure HTTPS, and if loading encounters error, reverts it back to HTTP' and is an app in the Web Browsers category. There are six alternatives to Smart HTTPS for a variety of platforms, including Windows, Linux, Mac, Firefox and Online / Web-based. The best alternative is HTTPS Everywhere, which is both free and Open Source. Other great apps like Smart HTTPS are HTTPZ (Free, Open Source), HTTPS Now (Paid), ForceHTTPS (Free, Open Source) and HTTP Nowhere (Free, Open Source).
HTTPZ is meant to be unobtrusive and lightweight. Is very configurable, and should be slightly more secure than some of the alternatives out there, since it has a couple of built-in ways to defend against SSL stripping attacks.