Core Themes

  • Flat Light (class com.formdev.flatlaf.FlatLightLaf)
  • Flat Dark (class com.formdev.flatlaf.FlatDarkLaf)
  • Flat IntelliJ (based on Flat Light) looks like IntelliJ theme from IntelliJ IDEA 2019.2+ (class com.formdev.flatlaf.FlatIntelliJLaf)
  • Flat Darcula (based on Flat Dark) looks like Darcula theme from IntelliJ IDEA 2019.2+ (class com.formdev.flatlaf.FlatDarculaLaf)

Differences between Flat Light/Dark and IntelliJ/Darcula themes

Flat Light

Flat IntelliJ

Flat Dark

Flat Darcula

IntelliJ Platform Themes

IntelliJ Platform based products (e.g. IntelliJ IDEA or WebStorm) support 3rd party theming thru plugins, which internally use JSON files (with extension .theme.json) to describe the UI theme.

FlatLaf supports loading such 3rd party .theme.json files and using them as a Laf.

  • Arc Orange
    Arc Orange
  • Dark Purple
    Dark Purple
  • Cyan Light
    Cyan Light
  • Nord

How to find a 3rd party IntelliJ theme?

Use the FlatLaf Demo, which bundles many popular open-source 3rd party themes from JetBrains Plugins Repository, to try them out. If you want use one theme in your application, click the "Save" button above the themes list to save the .theme.json file (and a license file) to your application source code.

You can also go to the JetBrains Plugins Repository and browse available IntelliJ theme plugins at If you found a good one, click on the "Source Code" link at the bottom of the theme page, which redirects you to the source code repository of the theme. There you can search for a .theme.json file and download it.

Tip: If you copy the a .theme.json file into the same folder as the FlatLaf Demo Jar, you can try this theme in the demo. Scroll the themes list down to the bottom and select the theme from the "Current directory" section.

How to use a 3rd party IntelliJ theme?

To use a .theme.json file in your application, save it somewhere into your application's resources (or src) folder and use following code to load and initialize it:

IntelliJTheme.install( MyApp.class.getResourceAsStream(
    "/com/myapp/themes/arc-theme-orange.theme.json" ) );

// create UI here...