You can get TeamCity plugins in the plugin repository.
Since TeamCity 2018.2, you can install plugins from the plugins repository.
Go to the Administration | Plugins List page and upload a plugin zip from your local machine using the corresponding link.
Installing a plugin manually
Copy the zip plugin package into the
<TeamCity Data Directory>/plugins directory. If you have an earlier version of the plugin in the directory (though the plugin package can be named differently), remove it.
Prior to TeamCity 2018.2, you need to restart the server to enable the plugin. If the plugin has an agent part, all the agents will be updated automatically. For plugins with the agent part only, the server restart can be skipped: the agents will be updated automatically.
Since TeamCity 2018.2, to enable plugin after installation, click the plugin context menu and select Load. The plugin will be enabled without server restart.
Uninstalling a plugin manually
Remove the plugin package from the
TeamCity Data Directory>/plugins directory and restart the TeamCity server.