Matrix is an open network for secure, decentralized communication - and
it has a web api.
A warning on message type: Using 'm.notice' breaks rendering on Element
for Android (no fixed width font) and does not pop up desktop
notification. Thus we use 'm.text'. Should be safe as we do not send the
messages in response to other messages.
https://matrix.org/
Christian Hesse
Michael Gisbers