Senior​/Principal Kotlin Engineer

Job Description

We’re 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’ll 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’re about writing great code, solving challenging problems, and shaping architecture from the ground up.

You’ll be joining teams working on genuinely greenfield, strategic rebuilds with clear scope, autonomy, and modern tech stacks. There’s 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 — no prior banking experience required.

This is a collaborative, trust-based environment where developers have real autonomy, clear ownership, and meaningful technical input. There’s 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’ll receive time off in lieu.

• 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 — this is a coding role first and foremost

• 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

These roles are hybrid, typically 2-3 days per week for team collaboration, with the rest of the time remote.

Permanent employees preferred, but contractor arrangements will also be considered.

We can only consider candidates who have the right to work in the UK and do not require visa sponsorship. Applicants must be UK-based and within a commutable distance to London.

Email careers with your CV and a brief introduction. Even if you’re not sure you tick every box, we’d still love to hear from you - we’re always keen to meet passionate, technically curious developers and can keep you in mind for future projects if this one isn’t the right fit.