How League of Legends broadcast overlays work
See how League Broadcast reads local game data and sends browser-source overlays to OBS Studio and other streaming software.
What is League Broadcast?
League Broadcast is a Windows production app for League of Legends esports. It creates champion select, in-game, and post-game graphics. Game data updates the overlays live, and your streaming software displays them as browser sources.
How does League Broadcast read game data?
League Broadcast reads game state on the PC running League of Legends. It updates overlays every frame.
API polling returns delayed samples. Pixel reading only captures visible information. Local game-state access provides frame-accurate updates.
Does League Broadcast work with Vanguard?
Yes. League Broadcast uses a Vanguard-compatible game-state source. It is the maintained successor to the original open-source LeagueBroadcast project.
How do overlays get into OBS or other streaming software?
The app serves each overlay as a local web page. Add it to OBS Studio or your streaming software as a browser source and place it over the game capture. The overlay updates live as the match runs. This works with any streaming software that supports browser sources.
For setup instructions, see the tournament broadcast guide. You can also download the app and test it with a match.
Where does League Broadcast run?
League Broadcast and the spectating League client run on the observer or production PC. That PC serves the overlays locally to your streaming software. Remote sessions are optional.
Do I need the Riot API or an API key?
No. League Broadcast reads game data locally, so you do not need a Riot API key or need to manage rate limits. We follow Riot's third-party tool policies.