Senior Full-Stack Kotlin Engineer (Freelance/Service Agreement)

Félix; Warsaw (IN); On-site; USD 120,000 - 180,000; Full time

Job summary

Félix seeks a Senior (Full-Stack) Kotlin Engineer to join a service‑agreement collaboration. You will help scale Flix station management software, working with a distributed, cross‑functional team to deliver robust backend services and solid frontend experiences for millions of users.

You will drive technical roadmaps with stakeholders, participate in agile ceremonies, perform code reviews, and ensure reliable CI/CD deployments to cloud environments such as AWS/Azure. Fluent English required.

Qualifications

• 5+ years of software engineering experience, backend with JVM and Kotlin.
• Solid frontend skills with modern frontend stack.
• Experience with event-driven architectures; exposure to event sourcing, CQRS, and DDD is a plus.
• Hands-on automation/ deployment to cloud infra with CI/CD and DevOps practices.
• Proficiency in system design and architecture.
• Strong written and spoken English communication skills.

Responsibilities

• Independent management of roadmap epics as topic driver with product owner alignment.
• Interact with business stakeholders to evolve the product vision.
• Support development in an agile environment.
• Pair and ensemble programming, code reviews, testing, and operations.
• Deliver new versions using CI/CD pipelines to cloud platforms.

Skills

Kotlin

Frontend skills

CI/CD

DevOps

Cloud AWS/Azure

System design

Job description

We are looking for a skilled Senior (Full-Stack) Kotlin Engineer as service agreement collaborator. Flix customers worldwide expect a comfortable and seamless experience at our stations as part of their travel experience. Our self-organized, cross-functional and distributed team builds products to enable Flix station managers to scale management of the station inventory, which a wide range of internal tech teams across Flix depend on, and overall serves to improve the experience at our stations for millions of passengers.

Scope of services

• Independent management of roadmap epics as topic driver, aligning technical requirements and solutions across the Flix teams together with the product owner
• Close interaction with business stakeholders on continuously developing and improving the product vision with business driven mindset
• Supporting the development process using an agile environment
• Pair and ensemble programming, code reviews, testing, and operations
• Delivery of new versions of the product, using continuous integration and delivery

Relevant experience

• 5+ years of software engineering experience, primarily backend development with a JVM language, including some commercial experience with Kotlin
• Solid front-end skills with modern front-end stack
• Experience with event-driven architectures; exposure to event sourcing, CQRS, and domain-driven design (DDD) is a plus
• Hands-on experience with automation and deployment of applications into cloud infrastructure (e.g., AWS, Azure) using CI/CD pipelines and DevOps best practices
• Proficiency in system design and architecture
• Solid written and spoken English communication skills