Firefox's HTTPS-only setting automatically opens all sites in HTTPS and displays an error if the HTTPS connection cannot be made. The override option is on a per-site basis, so you will still need to land on the site to disable HTTPS-only.

Alternatively, you could use HTTPS Everywhere extension instead which is based on a ruleset. This will not forcibly upgrade your work site to HTTPS since it does not appear on the list while still maintaining HTTPS everywhere else.

I used to use HTTPS Everywhere. I actually just removed it in favor of the built in Firefox behavior. All it is missing is the ability to toggle off HTTPS-only for a site with out requiring one to actually visit the site first.

As it turns out I have a solution, but it involves poking around in your firefox internals. I'm sure all the usual warnings about "you break it, you bought it" applies here.

I discovered that the site specific HTTPS-only settings are stored in $profile/permissions.sqlite. I closed firefox and inserted a new row that looks something like this:

"4375,http:${url},https-only-load-insecure,1,0,0,1617224928601"

I would love to see a better way to add exceptions rather than fiddling with sqlite files.

You can possibly use code in the Browser Console (not the Web Console) to add or remove "https-only-load-insecure" exceptions.

• https://developer.mozilla.org/en-US/docs/Tools/Browser_Console

const HTTPS_ONLY_PERMISSION = "https-only-load-insecure";
var myOrigins = ['http://example.com', 'http://example.org'];
function addException(uri){
Services.perms.addFromPrincipal(Services.scriptSecurityManager.createContentPrincipalFromOrigin(uri),HTTPS_ONLY_PERMISSION,1,0);
}
for (var i=0; i<myOrigins.length; i++) addException(myOrigins[i]);

const HTTPS_ONLY_PERMISSION = "https-only-load-insecure";
var myOrigins = ['http://example.com', 'http://example.org'];
function removeException(uri){
Services.perms.removeFromPrincipal(Services.scriptSecurityManager.createContentPrincipalFromOrigin(uri), HTTPS_ONLY_PERMISSION);
}
for (var i=0; i<myOrigins.length; i++) removeException(myOrigins[i]);