Zoom https://zoom.us
Allows notably the creation of break-out groups of students

Screenleap https://www.screenleap.com
Works with most browsers and devices. Allows you to share your own computer so participants can point on your screen.

YouTube https://www.youtube.com
Fast. On the website, click on the camera icon with a + and choose the "go live" option, create a name and an account if needed. You can restrict access (to students for example).

UberConference https://www.uberconference.com
Allows you to share the screen, talk to students and quickly share documents. Maximum of 50 participants. Free to use with no time limit. No access codes.

Skype https://www.skype.com
Classic. Compatible with all OS and media. Screen sharing, chat, "live" subtitles, document, video or audio sharing. One can record the meeting for re-use.

Join.me https://www.join.me
Allows you to create your own web address. Free access. Screen sharing, mobile, instant face-to-face meetings, chat, administrative control, custom wallpaper, etc.

Google Drive https://www.google.com/intl/fr/drive/
Enables collaborative work: preparation and presentation of documents (Google slides), sharing of documents or evaluations (Google Forms), with tracking of connected people and document modifications in real time.

Google Hangouts https://hangouts.google.com
Direct link from gmail account. Audio, video and text message. Screen sharing in the video conversation.

Seesaw https://web.seesaw.me
Developed for school pedagogy. User-friendly platform for students: Creation of content (text, drawings, recordings), revision and comments on content by teachers. Contact chat with teachers and parents.

Slack https://slack.com/intl/fr-ca/
Looks like Teams/Zoom. Creation of shared themes via specific channels. Teamwork, collaboration or other interactive activities. Search option in email, files, etc.

Kahoot https://create.kahoot.it/login
Online quiz. One can integrate images and videos. Very interactive. No limit to participants. Answers visible on the manager's screen only (must be used with another system in parallel if you want to view-share results). Question length limit. Reduced functionalities with the free version.

Go to meeting https://www.gotomeeting.com/en-ca/work-remote
Similar to Zoom/Skype. Allows many users at the same time. Screen sharing, conference calls, etc. 3 months free trial.