Grafana. It's free and open source. However, it's limited to a 5 seconds refresh rate and doesn't stream the data in - only polls data
We heavily use Grafana - It's not limited to 5 seconds that's just the default they ship it with, edit the template from the UI and it does 1 second without any issues.
Check our Brian Greig’s Medium article called “Websocket and Data Visualization”.