Nullala — system design canvas with simulation
Nullala is a free, browser-based tool for sketching and exploring system design diagrams. Drag databases, caches, message queues, load balancers, and API services onto an infinite canvas, connect them, and annotate with markdown notes.
Unlike a plain diagramming tool, Nullala can simulate request flow through your architecture, so you can watch traffic move through components and reason about bottlenecks, fan-out, and failure paths. Includes vim keybindings for editing labels and notes, drawing tools, and ready-made architecture templates. No account or signup required — this page loads the full editor.