If I remember correctly the UI for this existed long after Netscape Navigator. According to [1] it was removed in Firefox 44 in early 2016. I had expected that

If I remember correctly the UI for this existed long after Netscape Navigator. According to [1] it was removed in Firefox 44 in early 2016. I had expected that they only removed the UI but left the functionality available via about:config but that doesn't seem to be the case. EDIT: According to [2] and [3] it seems the behavior was triggered by about:config network.cookie.lifetimePolicy set to 1 (ASK_BEFORE_ACCEPT), but the meaning of 1 apparently has changed over the years. At least setting it to 1 doesn't trigger any cookie dialogs in my Firefox 70.0.1 (64-bit). [1] https://www.ghacks.net/2016/02/05/firefox-44ask-me-everytime-cookie-option-removed/ https://www.ghacks.net/2016/02/05/firefox-44ask-me-everytime... [2] https://bugzilla.mozilla.org/show_bug.cgi?id=233339 https://bugzilla.mozilla.org/show_bug.cgi?id=233339 [3] http://kb.mozillazine.org/Network.cookie.lifetimePolicy http://kb.mozillazine.org/Network.cookie.lifetimePolicy