Tools for describing JSON schemas

I'm writing a spec and need to describe some JSON objects. Big JSONs tend to get too confusing with text and tabs alone. Is ther开发者_如何学Pythone any online (preferably) tool to create diagrams like the ones on http://www.json.org/ or http://www.sqlite.org/lang_altertable.html. They use them to describe syntax, but, is there anything like it to describe JSON objects ? They are great to represent objects that are required, optional, arrays, etc.

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These types of syntax diagrams are known as "railroad diagrams".

There is an online tool at http://bottlecaps.de/rr/ui that you can use to generate tour own diagrams. You must specify your grammar in EBNF notation.