OBS is a popular free and open source live streaming software.
Add to OBS means you can add the Zap Alerts overlays, text-to-speech and widgets to your live stream through OBS. This means your live stream can display live Zap Alerts and messages attached to zaps from your viewers as well as other information in a fully customizable way.
Here is a screenshot from OBS showing the software running multiple Zap Alerts widgets.