In addition to explaining JSON, it also has a built-in JSON linter so you can enter JSON have have it validated, stringified, and Unicode encoded, right from the docs page.
One pain point if you’re generating JSON by hand on a device and publishing it is making minor JSON syntax error in your code. The JSON event decoder monitors published events and decodes and validates the JSON. If there’s a syntax error in your event, you can mouseover to get the error.
There’s also a huge section on using mustache templates, and an interactive mustache template tester.