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Agentic Java2Kotlin Eval Pipeline

Description

The core focus of this internship is to enhance, evaluate, and scale an LLM-based Java-to-Kotlin (J2K) translation tool. The intern will be responsible for the following key tasks:

  • Pipeline Expansion: Expand the current evaluation pipeline by adding a robust set of Java and Kotlin (Gold Kotlin) examples sourced from GitHub.

  • Framework and LLM Integration: Scale the pipeline to evaluate a wider variety of agent frameworks and LLMs. This includes integrating Claude Code, Codex, Gemini, various open-source models, and self-hosted offline models.

  • Evaluation & Dataset Creation: Analyze evaluation data (using methodologies similar to OpenAI or Anthropic evals) to identify areas where the models underperform, with the goal of creating a reinforcement learning (RL) dataset to improve open-source models.

  • AST/PSI Analysis: Implement heuristic-based methods to find and pair code declarations between Java and Kotlin using abstract syntax trees (AST) or Program Structure Interface (PSI) to systematically measure translation accuracy.

  • (optional) Offline Model Testing: Host and evaluate local models to test the feasibility of shipping a fully offline version of the J2K translation tool that still delivers quality results.

  • Final Deliverables: By the end of the project, the intern should deliver a comprehensive evaluation setup for various agent frameworks, define specific performance metrics for the J2K tool, and implement tangible improvements to the tool through refined prompting, code adjustments, or a combination of both.

Requirements

The ideal candidate should have a mix of standard programming skills and specialized experience with AI models.
Core Requirements:
Solid proficiency in Java.
Solid proficiency in Kotlin.

  • Practical experience working with LLM Agents.

Strong Pluses:

  • Previous experience writing plugins for IntelliJ IDEA.

  • The ability to write custom skills or tools for Claude.

Nice-to-Haves:

  • Experience in building and running formal LLM evaluations (evals).

  • Knowledge of compilers and code structures (AST/PSI).

Admission

Internship Projects Fall 2026

Contact details

internship@jetbrains.com

Preferred internship location

Netherlands

Technologies

Java
JVM
Kotlin

Area

Development
Research

Internship timing preferences

Part-time acceptable
Start ASAP
Applications by 08.05.2026
Interview by 30.05.2026
Feedback and final results by 12.06.2026