https://atom.io/packages/regex-railroad-diagram https://atom.io/packages/regex-railroad-diagram The main diagram and regex packages are separate node packages,

https://atom.io/packages/regex-railroad-diagram https://atom.io/packages/regex-railroad-diagram The main diagram and regex packages are separate node packages, by the same author. It's nice because it automatically detects when your cursor is in a regex and opens a bottom panel. works for js and Python.