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The Berkeley Lab's Indico instance is hosted at https://conferences.lbl.gov
Indico is an open source web application developed at CERN which facilitates the organization of events of all sizes, ranging from meetings and lectures to big conferences.
A full list of features can be found at https://getindico.io/features/, which includes reviewing workflows for scientific papers and their abstracts as well as a full-fledged room booking system.