Get it from plugin repository: https://plugins.jetbrains.com/plugin/9854-proselint
Plugin integrates Proselint in the IDE.
The plugin is built using Gradle and uses gradle-intellij-plugin to integrate with IntelliJ Platform.
To build a plugin run
$ ./gradlew buildPlugin
Plugin zip file will be created in build/distributions
To test plugin in IDE run ./gradlew runIdea
Plugin is written in Kotlin.