If you make third party web applications, Javascript or whatnot to include on someone else's page, then Charles or similar is a must-have when you have non-tech

If you make third party web applications, Javascript or whatnot to include on someone else's page, then Charles or similar is a must-have when you have non-technical and semi-technical people helping with customer issues. Almost anyone can use Charles to make the simple assessments of a problem, root cause, wolf-fencing, etc. In the technical groups, Charles can usually be bettered for ease of use by custom tools for specific use cases. It is pretty quick and easy to use the proxy libraries in Node.js to throw together internal tools with a command line interface, for example.