May 12, 2026

Kotlin Engineer – (Senior/Staff)

Senior • Remote

23,500 - 31,000 PLN

Krakow, Poland

VirtusLab is a leading European software consulting and engineering company, home to over 350 EU-based professionals. Our mission is to craft clean code and practical solutions with precision and purpose. We foster a dynamic culture rooted in strong engineering, a sense of ownership, and transparency, empowering our team. As part of the expanding VirtusLab Group, we offer a compelling environment for those seeking to make a substantial impact in the software industry within a forward-thinking organization.

About the role

We are looking for engineers interested in building various tooling using mainly Kotlin. Our team is working on IntelliJ plugin, IDEs, coding agents or frameworks for Local AI inference. Your job will be focused 100% on technology and your users will be developers. You will work withing, small, flexible team and you will have a lot of authonomy: you will be responsible for design, scope, testing and implementation. You will work with tooling engineers, and you will be part of an organisation specialized in developer tooling.

Kotlin/Java Expert

Kotlinx.coroutines / concurrent programming Advanced

Compose Desktop (Jetpack Compose) Nice to have

Kotlin multiplatform Nice to have

Build tools/IDE development Nice to have

English Advanced

Project

Local Inference Platform

Project Scope

We are building a desktop application for deploying and configuring local inference on local devices (e.g. NVIDIA Spark / DGX Spark), managing model lifecycle (start/stop), and connecting coding agents like Claude Code and Codex to locally hosted models. Currently an internal MVP, on the road to open source.

Tech Stack

Kotlin, Compose Desktop (with JetPack Compose roots), kotlinx.coroutines, REST APIs for model deployment management

Agent layer: configuration files in toml/json/yaml, LLM proxy routing from agents to BE

Packaging: native installers — msi (Windows), deb (Linux), dmg (macOS) 

Challenges

Building a desktop control plane for local AI agents that abstracts away the messy parts of running LLMs on heterogeneous hardware — model lifecycle, proxy routing, agent configuration, and OS-specific quirks (path separators, signing, packaging) — while keeping the system extensible enough to evolve toward open source. Visualising model statistics and system load on top of a backend that actually does the deployment.

Team

Small, startup-like team on the JetBrains side — no bureaucracy, direct contact with potential users, fast iteration. Code reviews as part of the process.

What we expect in general

  • Strong Kotlin skills or Strong Java expertise with knowledge of Kotlin

  • Understanding of asynchronous and concurrent programming, at best with Kotlin Coroutines

  • High agency and ability to drive work in a changing environment

  • Engineering pragmatism: cutting complexity while keeping the system extensible

  • Hands-on experience using LLMs daily, with the judgment to know when they help and when they don’t

  • Fluency in English, with good communication skills for a remote-first team

  • Self-motivation and the ability to take full ownership of features end-to-end

Nice to have

  • Experience with different LLM agents and their configurations

  • Experience with IDE development, especially around JetBrains IDEs

  • Hands-on experience with developer tooling (compiler, build tools, linters, IDE, agents)

  • Experience with creating OS-native, desktop applications

  • Experience with creating GUIs using JVM (Swing, SWT, etc.)

A few perks of being with us

  • Building tech community

  • Flexible hybrid work model

  • Home office reimbursement

  • Language lessons

  • MyBenefit points

  • Private healthcare

  • Training Package

  • Virtusity / in-house training

And a lot more!

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Kraków, Poland

140 - 185 PLN

🏢 Summary: Engineering role focused on building and standardizing SDK libraries and API integrations for distributed ledger financial products. The position involves advanced TypeScript development, API design, OpenAPI optimization, and contribution to Scala-based tooling in a distributed international environment. 🗂️ Requirements: Strong TypeScript proficiency, Experience developing reusable SDKs and libraries, Deep understanding of API design, Ability to work with Scala codebases, Experience with OpenAPI definitions, English level B2/C1 📃 Skills: TypeScript, Scala, Tapir, OpenAPI, SDK, API, DLT 🏢 Description: VirtusLab is a leading European software consulting and engineering company. Our mission is to craft clean code and practical solutions with precision and purpose. We foster a dynamic culture rooted in strong engineering, a sense of ownership, and transparency, empowering professionals to make a substantial impact in the software industry. About the role This engagement is focused on architecting and delivering the developer experience and integration layer for high-stakes Distributed Ledger Technology (DLT) financial products. The project requires a specialized engineering partner capable of executing deliverables across a hybrid environment that combines expert-level TypeScript depth with the ability to competently interface with a Scala codebase. Project Scope We are working on the project together with a partner from the Smart Contracts industry. We are contributing to key components of the platform in the area of Distributed Ledger Technology (DLT). The work is divided between several teams responsible for individual components and the performance of the solution. The product is used by large international companies in the financial industry. This engagement is focused on Software Developer Kit libraries and API definitions around a wallet application that is built on top of a distributed ledger. The scope of cooperation covers SDK Evolution & Standardization: Extending and polishing the existing Wallet SDK libraries in close collaboration with product teams, while driving the design of new, multi-language client library standards with a reference implementation in TypeScript. Ledger API & Code-Gen Optimization: Refining and smoothing the Ledger API’s OpenAPI definitions using Tapir (Scala) and maintaining Scala-based code-generation tools. This autonomous role requires deep expertise in API design to deliver clean, production-ready interfaces. Tech Stack TypeScript, Scala, Tapir, OpenAPI Project Environment The initiative is driven by a Switzerland-based distributed team, interfacing directly with a Product Manager responsible for the project’s business vision. What we expect in general Strong fluency in TypeScript and its advanced design patterns. Proven experience in developing reusable libraries and SDKs. Deep understanding of APIs (from both client and server-side perspectives). Ability to competently contribute to the Scala codebase (specifically for tools and API generation). Good command of English (B2/C1). A few perks of being with us Building tech community Flexible hybrid work model Home office reimbursement Language lessons MyBenefit points Private healthcare Training Package Virtusity / in-house training Access to the above perks is optional and completely voluntary for B2B contractors

Technology

VirtusLab

Software Engineer with LLM (Expert)

Senior

Hybrid

Krakow, Poland

26,000 - 31,000 PLN

🏢 Summary: Opportunity to join a newly formed, globally distributed team building an AI-powered internal developer platform for a large-scale engineering organization. The role focuses on designing and integrating LLM-based tools and agent systems that enhance coding, testing, and deployment workflows. You will help architect and implement core AI infrastructure and integrations within a greenfield, startup-like environment. 🗂️ Requirements: Hands-on experience integrating or building with LLMs, AI agents, or coding assistants, Strong experience in Scala or another modern JVM language (Kotlin or Java 17+), Proven polyglot programming ability, Experience designing and implementing API integrations, Ability to collaborate in a distributed team across time zones, Professional English communication skills 📃 Skills: Python, TypeScript, Scala, Java, Kotlin, LLM, OpenAI, Anthropic, API, AWS, GRPC, MySQL, GitHub, Slack, Docker, Kubernetes, GCP, CI/CD 🏢 Description: We foster a dynamic culture rooted in strong engineering, a sense of ownership, and transparency, empowering our team. As part of the expanding VirtusLab Group, we offer a compelling environment for those seeking to make a substantial impact in the software industry within a forward-thinking organization. About the role You will be a founding member of a new, globally distributed team dedicated to a single mission: revolutionizing internal developer experience in a big technical organization (thousands of developers) via AI-based developer tools. Project scope You will be a founding member of a new, globally distributed team dedicated to a single mission: revolutionizing internal developer experience in a big technical organization (thousands of developers) via AI-based developer tools. Think of it as an internal startup, with the freedom to innovate and the stability of an established company. Our goal is to design and build an intelligent platform that assists developers at every stage, from coding and debugging to testing and deployment. Your team will be part of a larger 10-person group, with colleagues in California, Amsterdam, and Poland, organised into three focused sub-teams. This role requires collaboration (few meetings a week) with engineers on the US West Coast to ensure our platform meets the needs of our global team. What you will do Design and implement integrations with cutting-edge Large Language Models (LLMs) and APIs (like OpenAI’s models, Anthropic’s Claude, and more). Develop intelligent, agent-based systems to automate and assist in complex software development tasks. Engineer the core infrastructure for our AI agents, including components like MCP servers. Seamlessly weave AI capabilities into the daily workflows of our developers by integrating with essential tools like GitHub, Slack, IDEs, and client internal services, mostly Scala-based. Collaborate within a distributed, international team to research, prototype, and deploy solutions that have a direct impact on developer productivity and satisfaction. Tech stack This is a greenfield project, which means you’ll have a say in the technologies we choose. Nothing is set in stone. However, our environment and the problem space suggest we’ll be working with: Primary Languages: Python, TypeScript, Scala – based on available APIs and existing integration – but actual stack will be determined as the project progresses. The project will be based on internally developed services and solutions, utilising Scala, Java, AWS, GRPC, MySQL and more. What we expect: Proven polyglot programming skills with the ability to rapidly learn new languages, frameworks, and domains. Hands-on, practical experience building with or integrating LLMs, coding assistants, or AI agents. You should be ready to demonstrate your work or discuss your implementation experience during the interview. Strong, hands-on experience in at least one of the following: Scala, or another modern JVM language (e.g., Kotlin, Java 17+). A proactive, self-starter attitude. You take initiative, communicate clearly, and thrive in a collaborative, goal-oriented environment. Excellent communication skills in English and the ability to effectively collaborate with team members in the US West Coast time zone. Nice to have: A passion for or prior experience in building developer tools, IDE plugins, or enhancing developer workflows. Experience with DevOps practices and tools (CI/CD, Docker, Kubernetes, cloud platforms like GCP or AWS). Familiarity with the MLOps or Data Engineering ecosystem, particularly on the integration and tooling side (we are not looking for model researchers or trainers) A few perks of being with us Building tech community Flexible hybrid work model Home office reimbursement Language lessons MyBenefit points Private healthcare Training Package And a lot more!