Kotlin/Java Developer (Koog)

At JetBrains, code is our passion. Ever since we started, back in 2000, we have strived to make the strongest, most effective developer tools on earth. By automating routine checks and corrections, our tools speed up production, freeing developers to grow, discover, and create.

The AI Agents Platform team at JetBrains is building Koog – an open-source framework for creating powerful, customizable AI agents. Koog brings efficient history management, persistent memory, task planning, streaming, and multi-agent orchestration to developers working with LLMs. Our mission is to push the boundaries of how AI systems are developed, integrated into, and run in real-world applications.

We are seeking a highly skilled Senior (or higher) JVM developer who thrives at the intersection of deep technical problem-solving and fast-paced AI innovation. You will work primarily with Kotlin, and Java where appropriate, helping to design intuitive APIs and build robust, production-grade tools for AI agent development.

In this role, you will: 

• Design and implement clean, maintainable, high-performance Kotlin and Java code.

• Create intuitive and extensible APIs for developers building AI agents.

• Rapidly iterate and experiment in response to quickly evolving developments in the fields of AI and LLMs.

• Research, test, and validate hypotheses in the LLM and AI space.

• Stay ahead of trends in LLMs, model APIs, and new tools across the AI ecosystem.

• Collaborate closely with researchers, designers, and product engineers to bring AI-powered developer tools to life.

We’ll be happy to have you on our team if you: 

• Have extensive knowledge of the JVM ecosystem, with at least four years of hands-on experience in Java or Kotlin development.

• Possess a solid understanding of data structures, algorithms, and system design.

• Are able to write fast, clean, and maintainable code.

• Exhibit motivation, curiosity, and adaptability in a rapidly changing AI landscape.

• Are committed to exploring new technologies, tools, and LLM advancements proactively.

We’ll be especially thrilled if you have: 

• Experience building or shipping AI agents or LLM-based chatbots.

• Familiarity with Ollama, cost optimization for LLM-based systems, or agent orchestration frameworks.

• Knowledge of Spring or other JVM frameworks.

• Contributions to open-source AI tools or agent platforms.

Why join JetBrains? 

• Work on a cutting-edge AI agent platform with a global impact.

• Contribute to the world’s most cutting-edge AI coding agents (SWE-agents), shaping the future of the IDE experience.

• Collaborate with a world-class team of passionate engineers, designers, and researchers.

• Enjoy flexible work options: remote, hybrid, or office-based.

• Receive competitive compensation and strong support for continuous learning.