Senior Kotlin Engineer (Event Streaming/Sourcing) - London

Senior Kotlin Software Engineer (Investment Banking) - London/hybrid Daily rate: £600 - £1000 Duration: 6 months Hybrid: 2 days on site Start: ASAP My banking client is looking for 2 experienced Senior Kotlin Software Engineers to join a cloud-hosted platform team within an investment banking environment. This is a fast-paced, front-office-facing role with a strong emphasis on high-quality engineering, reliability, and collaborative working practices. The role offers exposure to modern engineering practices and the opportunity to work closely with business stakeholders in a demanding and high-impact environment. Key Responsibilities • Design, develop, test, and maintain backend services using Kotlin • Contribute across the full software lifecycle: development, integration, and production support • Implement and support event-driven architectures, including event sourcing and event streaming • Work within an Agile/XP environment, utilising: • Pair programming • Mob programming • Test-first development practices • Build and maintain CI/CD pipelines and deploy services to cloud environments • Continuously refactor code and uphold high standards of code quality and reliability • Participate in architectural and technical design discussions • Collaborate closely with front office stakeholders and cross-functional teams • Deliver solutions within short timelines and respond to urgent business needs Essential Skills & Experience • Strong commercial experience developing production-grade Kotlin applications (non-Android) • Proven experience with Test-Driven Development (TDD) and test-first approaches • Hands-on experience with event-driven systems (event streaming and/or event sourcing) • Experience with CI/CD tools and practices • Strong background in refactoring legacy code and maintaining clean, maintainable systems • Experience working in Agile/XP environments, ideally including mob programming • Excellent communication skills with the ability to engage effectively with business/front office stakeholders Desirable Skills & Experience • Prior experience in investment banking or financial services, particularly front office systems • Experience with cloud platforms (AWS, GCP, or Azure) • Familiarity with containerisation technologies (Docker, Kubernetes) • Experience with Kafka or similar messaging/event platforms • Understanding of distributed systems design and immutable event patterns • Experience with observability, monitoring, and incident response tools • Exposure to low-latency or high-availability systems *Rates depend on experience and client requirements