It is a component of the ISteamGameServer interface that communicates with Valve to register a server's existence, map, and player count.

Around 2018–2020, Valve began shifting legacy GoldSrc and early Source engine games to a new server query protocol. Many older third-party server browsers (like HLSW or GameTracker) broke. More critically, self-hosted dedicated servers stopped reporting their existence to the Steam Master Servers.

Suddenly, his speakers crackled. A voice, thin and digitized, whispered through the static: "Thank you for the update. We’ve been waiting to spawn."

Most updater builds require a plain text config. Create config.ini in the same folder as the executable:

login anonymous heartbeat

The primary function of a master server updater is to "heartbeat" your game server's information to Valve's master servers. This allows players to find your server in the "Internet" tab of their game.

Downloading the Steam master server updater is a relatively straightforward process. Here are the steps: