Software Developer for ThinkRail (Innovation Hub)

Location: Belgrade, Serbia; Berlin, Germany; Limassol, Cyprus; Munich, Germany; Paphos, Cyprus; Prague, Czech Republic; Remote, Germany; Warsaw, Poland; Yerevan, Armenia

Department: Bonsai

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.

ThinkRail is an innovative project within JetBrains' Innovation Hub. Its aim is to develop a declarative programming language tailored to AI-spec-driven development. Our goal is to build an infrastructure that enables the efficient creation of complex systems with AI, while maintaining the trust of users and flexibility in the results.

Thinkrail is now open source and in alpha, and we’re entering the next stage of the product’s development: initial market penetration. We’re focused on bringing it into real-world projects and turning it into a robust, production-ready system. To help us get there, we’re looking for a software developer to join the team. You’d be joining at an early stage, with plenty of opportunity to influence the product, tooling, and architecture as they continue to evolve.

In this role, you will:

• Build and evolve ThinkRail’s developer tooling, including VS Code and IntelliJ IDEA plugins.

• Develop the language server, including analysis, completion, diagnostics, and verification.

• Improve the evaluator that turns specs into code and detects spec-code drift.

• Integrate ThinkRail with AI agent frameworks and protocols such as Koog, LangGraph, Spring AI, MCP, and ACP.

• Work closely with the founder and help shape technical decisions as the product evolves.

We will be happy to have you on our team if you:

• Are a senior backend or full-stack engineer who can work independently and take ownership of complex problems.

• Have strong engineering fundamentals. Most of our codebase is currently written in TypeScript, but we are flexible on your language background and care more about engineering depth than a specific stack.

• Are comfortable working in a small, fast-moving team with a high degree of autonomy.

• Have experience with developer tools, DSLs, static analysis, LSP, editor plugins, or AI agents — or are excited to work deeply in these areas.

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