This is an add-on or extension that works on Firefox and Chromium-based browsers (Chrome, Vivaldi, Brave, Microsoft Edge, etc.) with Scoutbook. It gives additional capabilities, some of them very useful. One of them is the ability to send messages only to people who haven’t RSVP’d to an event or to people who have said they were coming. That lets you send reminders only to people who haven’t RSVP’d or give special instructions to people who are.
For people dealing with Advancement, it has short cuts to make entering information quicker and easier.
Scouting forum for support
Full list of the capabilities.