This is a draft of a web software tool for drawing quick crease/slit patterns. Currently it works well for crease patterns that fit on an integer grid.

• Graph-based: Always maintain a planar graph, automatically subdividing and merging together touching vertices
• Draw a crease with two clicks or with dragging
• Recolor existing creases as different types by dragging over them (easily recoloring just part of a line)
• Fold angle support: enter degrees (or formula for degrees) to adjust mountain/valley fold amount (drawn via opacity)
• Erase existing creases by dragging over them
• Move vertices by dragging them (bringing all connected edges with them)
• Snapping to grid or existing vertex (e.g. from intersection)
• Cleanup to remove extra degree-0 or -2 vertices
• Undo/redo
• Save/export to .fold/.svg, including cutting (unwelding) of slits
• CLI for bulk conversion: node cpedit.js --cleanup --fold --svg filename.cp
• Title setting for document (file_title in fold format)
• Page size setting (width and height)
• Transform document by reflection or 90° rotation
• Keyboard shortcuts:
  • Escape key cancels current operation
  • z for undo, Z or y for redo
  • Modes and line types list their key shortcut

• Type npm install to do the necessary preparation
• Type git submodule update --init --recursive to use Origami Simulator integration
• Open cpedit.html in a web browser such as Chrome