Excalidraw

Pencils meet pixels here, where drawing feels loose and quick. Not quite perfect lines - that's the point of it. Sketching ideas works smoothly when thoughts jump fast between people online. Some folks stick to boxes connected by arrows, others map out wild concepts just fine. Nothing stops you from joining right away at zero cost. Pay only if needing extra room or features later on. Work stays saved outside your device too, grabbed whenever needed next time. Open it inside any browser, no downloads messing up your start. Watching someone else edit in real-time? That happens without delay.