title: Tool for generating railroad diagram used on json.org
body: <p>I love the syntax of <a href="https://en.wikipedia.org/wiki/Syntax_diagram" rel="nofollow noreferrer">railroad diagrams</a> on <a href="https://www.json.org/" rel="nofollow noreferrer">json.org</a> which are a graphical representation of the BNF language. I haven't found any tools that can produce results as eloquently.</p>
  <h2>Can anyone identify the tool used to generate these diagrams?</h2>
  <p><img src="https://i.stack.imgur.com/e3RRI.png" alt="" />
  <img src="https://i.stack.imgur.com/7Zcxu.png" alt="" /></p>