I needed to convert an Atom CSON grammar to a Sublime Text .sublime-syntax file. The process turned out more complicated than I expected, boiling down to these steps on my first go:

1. Convert .cson to .json.
2. Convert .json to .yaml.
3. Convert .yaml to .tmLanguage using https://github.com/jtojnar/relaxdiego-sublime-tools.
4. Fix the XML processing instruction in the generated .tmLanguage to use double quotes instead of single quotes.
5. Convert the .tmLanguage to .sublime-syntax using https://github.com/aziz/SublimeSyntaxConvertor.

Since this was fairly tedious, this article provides a simpler way to do all of this in one go, regardless of if your source-file is an Atom CSON grammar or a .tmLanguage file.

Just paste your Atom CSON or .tmLanguage document into the box below and the .sublime-syntax file will be generated for you.

^{(The conversion is happening entirely client-side, no requests to any external servers are made.)}