Kinopio - Thinking canvas for mind mapping, brainstorming, and moodboards

Drawasaurus - Drawasaurus is an online drawing & guessing game you can play with friends or strangers.

Kanboard - Kanboard is a free and open source Kanban project management software.

skribbl - Word guessing based on drawing.

Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.

gartic.io - Draw, guess, and win!