How the subathon timer works
A subathon is a stream that gets longer with every sub. This timer starts at the time you pick and adds seconds for every sub, resub, gifted sub and every 100 bits, using the values you set. It reads your chat the way a logged-out viewer does, so you never connect your account or give it any permission.
What counts
On Twitch, a sub or resub adds the seconds of its tier, and Prime counts as Tier 1. Every gifted sub adds the gifted sub time once: a gift of 20 subs adds it 20 times, and the announcement of the gift adds nothing. Bits add their share per 100. On Kick, a sub adds the Tier 1 time and a gifted sub the gifted sub time.
Where the time is kept
Everything runs in the browser source in OBS and is saved there, so reloading the source or restarting OBS keeps the time. The countdown keeps running while OBS is closed, but subs that come in while it is closed are not added. Nothing is sent to our server.
Kick support
Kick subs come from Kick's public chat events. Regular subs were tested on a live channel; gifted subs follow Kick's gift event, which we have not seen on a live channel yet, so check the log during your first stream.
Show the sub count too
Want the exact number of subs next to the timer? The Twitch sub count page has its own OBS widget.