No. The web version of the Event Maker is fully a cloud-based solution and, hence, requires a constantly working Internet connection.
Experienced organisers have provided us some tips on how to make sure your event can go on even in the case of Internet access issues
Have backup mobile connections. Portable mobile routers are not prohibitively expensive and all modern smartphones have Internet sharing (called e.g. Personal Hotspot in Apple iOS) functionalities. Web-version of Online Event Maker works nicely over normal 3G/4G connections.
Prior the event, create an Excel backup of all your key files - such as schedule, player reports and so on. So if the Internet goes down, you can continue working based on those files and fill the data to the Event Maker once the connectivity is back.