draw.io (diagrams.net)

draw.io (also known as diagrams.net) is a web‑based diagramming application that lets users create flowcharts, wireframes, UML diagrams, network maps, and other visual representations. It offers a drag‑and‑drop canvas, extensive shape libraries, real‑time collaboration, cloud storage integration, and export options for PNG, SVG, PDF, and more. Ideal for designers, developers, and product teams needing quick, flexible visual documentation without installing software.