🟨satblocksSystem Block Diagram Editor

Manifest: Edit and apply the manifest to add or remove components. Indicate multiple units of a component with xN. Use Load file to load a manifest from a .txt file.
Draw: drag between boxes. Press or release near an edge to pin that face (the edge highlights); press the middle to let the router pick the best face (the box outlines).
Select: click a line or box. Shift-click adds. Del removes lines, Esc clears.
Merge: select 2+ lines of one type to share a bus trunk. Unmerge separates selected merged connectors.
Display: select a component with ×N to switch single / stacked / multiple.
Autoroute: after drafting connectors, use autoroute to automatically reroute all connections for legibility.
Heritage: select a component, then choose a heritage level from the dropdown on the right.
Saving: the sheet autosaves in this browser; use Save / Load .json to work on multiple projects, or move a project between machines.
Ready.
© 2026 thaddeus jones