HiCal has been unavailable due to a fire that occured on March 10th in a data center in Strasbourg, France. We are sorry for the inconvenience.
Regarding the iPhone/iPad app, please update to version 2.0.12 to continue using HiCal. Regarding the Android app, please update to version 2.0.5.
For more information about the consequences of the incident, please check our Q&A page