Here I am sharing the tools I have used for causal loop diagramming:-
Paper and pen or pencil and eraser *Great for developing your own or group CLDs in place together*
Whiteboard or Blackboard *Good for collaboration in place*
Tablet (iPad) and pen *A personal whiteboard*
Miro or Jamboard: Miro site 
Google Jamboard
*Great for collaboration. No analysis tools.*
Loopy: Access site
*Online, Colourful, Brings CLDs to life, Engaging for kids, Ideal for simple models*
Cauzality: Access site
*Online, Free version available, Collaborative, Directive, Loop and polarity identification, Misses driver trees*
Vensim PLE: Access site
*Free to use for public learning, Powerful, Loop identification, Limited (2 levels) Driver trees, Stock flow diagrams, Full simulation capability*
Vensim Pro:Access site
*As PLE plus full depth driver trees. And massive simulation capability BUT expensive to purchase - sliding scale of charge depending on use profile*
Plectica: Access site
*Multiple perspectives, Online, synchronous and asynchronous, free version*
Kumu:Access site
*Tricky to use, great for highlighting loops*
Insightmaker:Access site
STELLA, iThink: Access site
*Supports stock flow diagrams and simulation*
Powersim: Access free tools
*Stock Flow diagram and simulation*