React Native Mobile Developer

KM3 Job Overview

We are looking for a senior React Native iOS mobile developer to join our team building the mobile app for our flagship portfolio management platform. This platform is used by portfolio managers and analysts across Equity, Fixed Income and Multi-Asset to both manage their portfolios and place orders. In this role you will design, develop, modify, adapt and implement short and long-term solutions to enhance and expand this functionality.

• Delivering functionality enhancements across the Equity screens, including the Orders workflow.
• Driving cross-domain improvements to shared controls and components.
• Improving app reliability and observability through expanded E2E test coverage, telemetry, monitoring etc.
• Providing support for the application and its users.

• Performing as a domain expert across the software lifecycle (coding, testing, deployment), leading significant pieces of development.
• Leading code reviews and actively participating in providing feedback on others' designs and code.
• Being accountable for technical debt in your own software.
• Owning complex technical problems — breaking them down methodically, making tactical vs. strategic trade-offs, and adapting your approach as new information emerges.

• Leading projects, work streams, or a small project team as required.
• Mentoring and supporting team members, particularly junior developers, and actively suggesting improvements to team practices.

• Able to work directly with business partners in an asset management context.
• Can articulate business needs and translate them into technology solutions.
• Buy or sell side Equity domain knowledge.

• React Native – Proven track record of shipping and maintaining high-scale, production-ready React Native applications. You should have experience managing the full lifecycle of an app that real users depend on — from feature development through to release and ongoing maintenance.
• Expert Type Script – Deep comfort with advanced Type Script patterns and ensuring strict type safety across Redux and navigation layers.
• Advanced State Management (Redux Toolkit + Saga) – Ability to architect and maintain complex state using Redux Toolkit and Redux Saga. Proficient with normalised state and advanced saga flows including error handling.
• Mobile CI/CD & Fastlane – Hands‑on experience owning and debugging non‑trivial CI/CD pipelines (Git Lab preferred). This includes multi‑environment builds, code signing via Fastlane Match, artifact publishing, and managing child pipelines.
• Testing Discipline – A test‑first mindset with proficiency in Jest and React Testing Library, focusing on accessible querying by role and text. Comfortable with sophisticated mocking strategies and E2E frameworks such as Detox.
• iOS Build Toolchain – Solid understanding of the iOS ecosystem including Xcode, Cocoa Pods, simulators, and provisioning profiles. Able to independently troubleshoot build failures and signing issues.

• React Navigation – Experience implementing and typing complex navigation patterns (stack, tab, and nested navigators).
• Mobile UX/UI Sensibility – A sharp eye for design and the ability to build intuitive interfaces that maximise limited mobile screen real estate.
• AI‑Assisted Development – Proficiency with modern AI tools (Copilot, Cursor, etc.) to accelerate workflows and code quality.
• Data Visualisation – Experience rendering performant charts, graphs, or dashboards within a mobile context.
• Real‑Time Data – Experience with Web Sockets or transitioning applications from polling‑based sync to real‑time architectures.
• Form Management – Experience handling complex user input using Formik and Yup.
• Previous asset management/financial services experience is useful but not required.

This position requires at least two days a week in our London office (up to three day WFH).