I will use the opportunity to mention our own tool: https://rest.secapps.com/ - some of you may find it useful

It has vars and rich text editing like Paw, i.e. you can build complex transforms by nesting what we call text items. Here is a blog post how this is done in practice: https://blog.websecurify.com/2017/02/hacking-node-serialize....

We are still working on the UX but there are a lot of cool features in the pipeline.