JQuake is a free software that helps you monitor real-time shaking events in Japan.
It displays individual seismic monitoring stations (owned and operated by NIED), displayed in values of either PGA or Seismic Intensity. JQuake also can receive and display Earthquake Early Warnings, which are provided by the Japan Meteorological Agency (JMA), that can warn you in advance* of shaking.* Due to limitations of the Earthquake Early Warning system, you may not receive a warning before shaking begins. Please refer to this document from the JMA for more information: https://www.jma.go.jp/jma/en/Activities/eew3.html
JQuake is developed by a small team of people in their free time out of passion and interest for earthquakes and Japan.
Other software in the field of seismic data monitoring exist in Japanese only. Here are some of our favourites: