May be useful but it just breaks some sites. I no longer can login into some sites that mix HTTPS and HTTP requests (for example with login and CAPTCHA elements). Needs some improvement.

works great with duck duck go's extension. These are the only 2 you need.

Please add a button (function) allow only HTTPS and block all http. Thank you.

Works well in most cases but does not revert to http on a mixed page causing incorrect display.

After installing you will never be able to search a word from url bar.
Just do not install it!

Very good Addon.
I was using HTTPS Everywhere before which is crap (did not redirect to HTTPS on all websites).

Work in firefox 58.0.2
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Всё работает на Firefox 58.0.2

It does nothing on firefox 57.

It doesn't revert to http when encounters error. It also blocks some scripts in http only pages.