Here I am sharing the tools I have used for causal loop diagramming:-
Paper and pen or pencil and eraser
Whiteboard or Blackboard
Tablet and pen
Miro or Jamboard: Miro site 
Google Jamboard
Plectica: Access site
Kumu:Access site
Insightmaker:Access site
Loopy: Access site
Online, Colourful, Brings CLDs to life, Engaging for kids
Cauzality: Access site
Online, Collaborative, Directive, Loop and polarity identification
Vensim PLE: Access site
Free, Powerful, Loop identification, Driver trees, Stock flow diagrams, Full simulation capability
Vensim Pro:Access site
Full depth driver trees
STELLA, iThink: Access site
Supports stock flow diagrams and simulation
Powersim: Access free tools