Code2Flow - An easy solution to create product flows.
PGF and TikZ - PGF/TikZ is a tandem of languages for producing vector graphics from a geometric/algebraic...
asciiflow - Infinite ASCII diagrams, save to Google Drive, resize, freeform draw, and export straight to text/html.
Diagrams Haskell package - Diagrams is a powerful, flexible, declarative domain-specific language for creating vector...
Flowchart.js - Draw SVG flow charts from simple text representations of the diagrams.
LaTeXDraw - LaTeXDraw is a graphical drawing editor for LaTeX.