Flowchart Tools
smartdraw
free to use. paywall to export anything?! useful swim lane feature to auto-outline flowcharts with grid
draw.io
FOSS Desktop client built on Electron, JS & Shell - can't view or edit plain SVGs?! - diagrams saved as XML
Sources: Flowchart Maker & Online Diagram Software GitHub - jgraph/drawio-desktop: Official electron build of diagrams.net