Hello fedi! This is Drawpile, the collaborative drawing program. It's public software under GPLv3.
It lets multiple people draw and animate on the same canvas together. Also usable offline, it's fast and runs pretty much everywhere.
Get it at https://drawpile.net/
Donate at https://donate.drawpile.org/
Feel free to shoot suggestions, feature requests or bug reports here on fedi, but for faster responses use the channels listed on https://drawpile.net/help/