Candidates:

- https://ballerina.io/learn/vs-code-extension/implement-the-c... Data Mapper is pretty spot on, but is ballerina, a language I'm not familiar with yet. Does this exist for Javascript?

- https://www.postman.com/product/flows/ - can this do object mapping or only "steps" of the flow?

- Another one I found just now, but it's not "visual" https://jolt-demo.appspot.com/#incept