Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.
Planning Poker - Open source implementation of planning poker game (collaborative online estimation/voting tool).
Kanboard - Kanboard is a free and open source Kanban project management software.
Firepoker - Agile Planning Poker powered by Firebase and AngularJS
ScrumDesk - ScrumDesk is an online scrum project management tool for small or medium size agile teams which apply Scrum or Kanban.
PlanITpoker - PlanITpoker is a cool on-line planning poker app that helps Agile project teams estimate projects easily.