Kotlin developer job description

About the role
We are looking for a Mid Kotlin Engineer to build and maintain backend services used by product teams and customers. You will work in a remote engineering team, ship production code regularly, and improve services written in Kotlin 2.x on JDK 21 with Spring Boot 3.x or Ktor 3.x.

What you'll do
- Implement APIs, workers, and integrations with clear tests.
- Model business rules using idiomatic Kotlin, null-safety, and readable data types.
- Debug production issues with logs, metrics, traces, and database queries.
- Participate in code review, planning, and incremental refactoring.
- Maintain Gradle Kotlin DSL builds and CI checks with support from senior engineers.

What you'll bring
- Professional Kotlin or Java experience and comfort moving between both.
- Understanding of HTTP APIs, relational databases, testing, and Git workflows.
- Practical knowledge of coroutines or willingness to learn them carefully.
- Ability to explain trade-offs and ask for help early.

Nice to have
- Experience with PostgreSQL, Kafka or similar messaging, Docker, OpenTelemetry, MockK, JUnit 5, ktlint, or detekt.
- Familiarity with remote collaboration across UK or US time zones.

About the role
We are looking for a Senior Kotlin Engineer to own important backend services from design through production support. You will make technical decisions, mentor other engineers, and help keep Kotlin systems reliable, observable, and easy to change. The stack includes Kotlin 2.x, JDK 21, Gradle Kotlin DSL, Spring Boot 3.x and/or Ktor 3.x, PostgreSQL, messaging, and cloud deployment.

What you'll do
- Design service boundaries, APIs, persistence models, and failure handling.
- Lead implementation of complex features across multiple modules or services.
- Improve latency, reliability, test coverage, build quality, and operability.
- Review coroutine, transaction, and integration code for correctness under load.
- Guide refactoring of legacy Java/Kotlin areas without disruptive rewrites.
- Mentor mid-level engineers through reviews, pairing, and design feedback.

What you'll bring
- Strong Kotlin backend experience in production systems.
- Sound judgment around coroutines, blocking IO, transactions, serialization, and API evolution.
- Experience diagnosing incidents using metrics, traces, logs, and profiling tools.
- Ability to communicate trade-offs clearly with product and engineering partners.

Nice to have
- Experience with modular monoliths, event-driven systems, OpenTelemetry, Testcontainers, KSP, detekt, or library APIs consumed from both Kotlin and Java.

About the role
We are looking for a Lead Kotlin Engineer to set technical direction for a remote backend team while remaining close to the code. You will own architecture for a product area, raise engineering standards, and help engineers deliver dependable Kotlin services without unnecessary complexity. The environment uses Kotlin 2.x, JDK 21, Gradle Kotlin DSL, Spring Boot 3.x and/or Ktor 3.x, cloud infrastructure, relational databases, and asynchronous processing.

What you'll do
- Define architecture, module boundaries, and integration patterns for a product area.
- Lead design reviews and turn ambiguous requirements into safe delivery plans.
- Establish Kotlin standards for testing, observability, error handling, and build tooling.
- Coordinate incident follow-up, technical debt decisions, and cross-team dependencies.
- Coach senior and mid-level engineers through feedback, pairing, and delegation.
- Contribute code in high-risk or foundational areas when needed.

What you'll bring
- Deep Kotlin backend experience and a track record of production ownership.
- Ability to balance delivery, reliability, maintainability, and team growth.
- Strong understanding of coroutines, transactions, distributed systems, and API design.
- Clear written communication for remote design decisions and technical alignment.

Nice to have
- Experience leading modular monolith or service-platform efforts, migrating Java to Kotlin, OpenTelemetry adoption, Gradle convention plugins, or Kotlin Multiplatform evaluation.