Senior Kotlin Developer

Salt; Greater London; Hybrid; GBP 70,000 - 90,000; Full time

Job summary

Salt is looking for a Senior Kotlin Developer to work on a cloud-hosted platform in Investment Banking. The role emphasizes Extreme Programming practices and involves supporting a high-caliber front office engineering team in London.

As a hands-on engineer, you will help replace a legacy bookbuilding system while ensuring high standards of code quality and system reliability. Ideal candidates will have strong Kotlin experience and cloud expertise, especially with GCP.

Qualifications

• Strong commercial experience building backend services using Kotlin.
• Experience with event-sourced and event-driven architectures.
• Deep familiarity with XP practices and clean code principles.

Responsibilities

• Work primarily in mobs, sharing ownership of design and code.
• Build, test, and evolve services focusing on clarity, simplicity, and maintainability.
• Support the platform in production, improving system design and resilience.

Skills

Kotlin

XP practices

GCP

CI/CD

Tools

GKE

Cloud Run

Cloud SQL

Job description

Senior Kotlin Developer (XP, GCP) – Investment Banking – London/Hybrid

Duration: 6 months

Start: ASAP

My client is looking for an experienced Senior Kotlin engineer to support and extend a cloud-hosted platform used for bookbuilding issuances within Investment Banking Capital Markets. You will join a high-calibre London-based front office engineering team working on a next-generation issuance platform replacing a legacy bookbuilding system.

This is a hands‑on engineering role with a strong emphasis on Extreme Programming (XP) practices, including mob programming, test‑driven development, and continuous refactoring. Engineers are expected to contribute across development, integration, and production support, collaborating closely to maintain high standards of code quality, system reliability, and performance.

• Strong commercial experience building backend services using Kotlin
• Experience with event‑sourced and event‑driven architectures
• Deep familiarity with XP practices, including:
• Mob programming as a primary way of working
• Continuous refactoring and clean code principles
• Cloud experience with GCP, including:
• GKE and/or Cloud Run
• Cloud SQL and Memory store
• Artifact Registry and Cloud Logging
• Key Management
• Experience with CI/CD and SDLC in regulated or enterprise environments
• Comfortable working on production systems requiring high availability and accuracy

Engineers in this role:

• Work primarily in mobs, sharing ownership of design and code
• Build, test, and evolve services with a strong focus on clarity, simplicity, and maintainability
• Support the platform in production, using incidents and defects as opportunities to improve system design and resilience