jammr is an interval-based jamming system. That means everyone is playing live but it is not real-time.
From the Frequently Asked Questions page (
https://jammr.net/faq.html):How does jammr work?
jammr sends your audio to other users and receives their audio. In order to avoid lag, jammr is “live” but not “real-time”. This means other players hear you after a fixed amount of time. This fixed amount is called the interval and can be set to fit the chord progression you are jamming to. This allows you to jam synchronised with people from all over the world.
Why is jammr not real time?
At the speed of light it takes 67 milliseconds to go half-way across the world. This means jamming with someone halfway across the world would be noticably laggy. Therefore, to ensure that you can jam with people from all over the world without delay we use intervals.