How to enable stylistic sets

Stylistic sets allow you to access additional, optional parts of the font on a per-feature basis. In Fira Code, they allow you to enable/disable alternative character variants.

Fira Code v2 supports these stylistic sets:

You can enable stylistic sets only if your editor supports it.

Atom

Go to Atom -> Stylesheet, add:

atom-text-editor {
  font-feature-settings: "ss01", "ss02", "ss03", "ss04", "ss05", "ss06", "zero", "onum";
}

Sublime Text

Go to Sublime Text -> Preferences -> Settings, add:

"font_options": ["ss01", "ss02", "ss03", "ss04", "ss05", "ss06", "ss07"]

For now Sublime Text does not allow you to specify zero and onum features.

VS Code

Since version 1.40, you can define in settings.json:

"editor.fontLigatures": "'ss01', 'ss02', 'ss03', 'ss04', 'ss05', 'ss06', 'zero', 'onum'"

To avoid possible bugs, you must uninstall Fira Code 1.x before installing Fira Code 2+.

CSS

.monaco-editor {
  font-feature-settings: "ss01", "ss02", "ss03", "ss04", "ss05", "ss06", "zero", "onum";
}

RStudio

Create or edit an rstheme file and add:

.ace_editor {
  font-feature-settings: "ss01", "ss02", "ss03", "ss04", "ss05", "ss06", "zero", "onum";
}

Some Apple apps

Adobe apps, MS Word etc

https://www.macworld.com/article/3052388/how-to-access-advanced-opentype-features-in-a-variety-of-mac-apps.html

Baking in stylistic sets into the font file

This might be an option if your editor does not let you choose stylistic sets on the fly https://github.com/twardoch/fonttools-opentype-feature-freezer