Kanboard - Kanboard is a free and open source Kanban project management software.
Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.
Kinopio - Thinking canvas for mind mapping, brainstorming, and moodboards
WBO - Realtime collaborative whiteboard
Wrike Scrum Boards - Wrike Scrum Boards is an online virtual whiteboard that allows individuals and team members to streamline their agile practice at every step.
Miro - Scalable, secure, cross-device and enterprise-ready team collaboration tool for distributed teams. Join 2M+ users & 8000+ teams from around the world.