Zoom
A popular video conferencing platform that can host individual or group sessions; it is encrypted and uses USA servers, please note that the USA does not need to comply with GDPR (data protection). I set security settings to avoid uninvited people joining, such as, one time only meeting ID's with passwords, a waiting room facility, and the 'lock room' function. Joining a meeting can be through the Zoom app or your internet browser.

Whereby.com
An alternative video conferencing platform that can host individual sessions or group sessions; it is encrypted and uses European servers so must comply with GDPR. It provides a locked room with a waiting room facility so no-one can enter the room uninvited. There is no need for an app as the room details can be typed into your internet browser.