Senior / Principal Kotlin Engineer

We 7re looking for several Kotlin developers, from experienced seniors to hands-on principal engineers, to join long-term greenfield projects with leading financial institutions in London.

You 7ll be part of small, high-calibre engineering teams delivering strategic rebuilds and modernisation projects, replacing legacy systems with clean, cloud-aligned solutions built on Kotlin and modern engineering practices. These are not maintenance roles - they 7re about writing great code, solving challenging problems, and shaping architecture from the ground up.

You 7ll be joining teams working on genuinely greenfield, strategic rebuilds with clear scope, autonomy, and modern tech stacks. There 7s little to no BAU work, and plenty of room to shape architecture, influence direction, and own your contributions end-to-end.

This is a great opportunity to deepen your Kotlin expertise, work alongside highly capable engineers, and gain exposure to large-scale systems and distributed architectures within major financial organisations 6 no prior banking experience required.

This is a collaborative, trust-based environment where developers have real autonomy, clear ownership, and meaningful technical input. There 7s a genuinely friendly culture in the team - people take pride in their craft and support each other to deliver excellent software.

Support work is minimal and usually voluntary; if you choose to assist, you 7ll receive time off in lieu.

Core Skills

• Strong Kotlin skills, with depth in modern engineering practices (TDD, clean code, SOLID principles)
• Demonstrated knowledge and hands-on experience in designing scalable, mission-critical systems
• Strong understanding of system integration and end-to-end test design principles
• Ability to work effectively in a collaborative, high-autonomy environment
• Experience with greenfield builds and/or incremental legacy replacement
• Strong problem-solving ability and architectural reasoning
• Hands-on mindset 6 this is a coding role first and foremost

Nice To Have

• Experience with large-scale data processing or distributed query systems (e.g. Spark, Beam, Flink, Trino, Presto, Hive, etc.), or the ability to quickly pick up similar tools
• Exposure to financial services or enterprise-scale systems