JetBrains Launches AI-Powered Java-to-Kotlin Tool for VS Code

Kotlin, developed by JetBrains, has traditionally been most closely associated with IntelliJ IDEA, while many development teams rely on Microsoft’s Visual Studio Code for mixed-language projects. Migrating established Java codebases to Kotlin can require more than a direct syntax rewrite, including changes for null safety and Kotlin conventions. Automating that work could reduce the time and engineering effort needed to modernize applications or change languages during development.

JetBrains introduced its Java to Kotlin, or J2K, extension for VS Code, according to a Feb. 24, 2026 report. Developers can convert a single .java file, multiple files or an entire folder from the context menu, then review the proposed changes in a side-by-side diff before accepting them. The extension supports GitHub Copilot Chat, Ollama, LM Studio and OpenAI-compatible services as language-model backends. It can also preserve Git history and configure Kotlin automatically for Gradle projects. No financial terms were disclosed.