Here is some brief info about the chrome browser plugin referred to as the Vote Counter on these forums.
The plugin can count votes, compile tallies, and do ISOs.
To install it, you need to install the Tampermonkey add-in for chrome. Then click this link to install the Vote Counter plugin.
The plugin installs a small menu in the thread header where you can enable the Vote Counter (actual name: Mafia Helper) functionality and do ISOs. There is also a menu in every post's header which among other things lets you see the current vote tally and post that tally to the thread. (Don't worry, the button takes you to the preview post screen first.)
The Vote Counter counts votes by identifying bolded statements starting with Vote: or Unvote.
So e.g. Vote: novice is counted as vote for me, and Unvote is technically counted as a vote for the unfortunate player named Unvote. Votes are counted in the order they're posted, you don't need to Unvote before changing your vote.
To get correct tallies you need to tell the plugin where in the thread a new phase starts, there's a "Start new day" link for this in the post header menu. You also have to allow the plugin to actually count all the votes in the phase, you do that by having the plugin enabled and then visiting every page of the thread. Once the plugin has the information needed to compile tallies, a "Post tally" becomes available.
It is also possible to get the plugin to work, somewhat clunkily, in Safari on PCs, iPhones and iPads:
The plugin was originally developed for the Realms Beyond forums and there is more information about the plugin over there.