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# Principal Software Developer (Web)

- **Company:** FlexTrade
- **Location:** London, UK
- **Experience:** Expert
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), Software Applications, Software Quality, IntelliJ IDEA, Mobile Application Software, JSON, Play Framework, Migration Manager, SonarQube, TypeScript, Web Applications, ReactJS, Backend, Gitlab, Build Management, React Native, Front End Software Development, Api Design, Jenkins
- **Published:** September 18, 2026
- **Apply:** https://www.indeed.com/viewjob?jk=f7f68edf37340d02

## About the Role

As Senior Web Developer, be part of our FlexONE team and own critical product surfaces across our web and mobile applications. You'll work end-to-end across a Scala + Play Framework backend, and a React + AG-Grid front-end, using gRPC for communication with our core product's backend systems. You will lead the technical direction as we build our Web app from an MVP to a comprehensive companion to the desktop application, as well as continuing the evolution of our Mobile app., Deep Full Stack expertise

 + Experience building & deploying production web apps, with significant experience in React and modern TypeScript
 + Willingness to take ownership of Scala backend (experience with Scala/Java preferred, but not required)experience with Scala/Java preferred, but not required)
 * Mobile Capability: Experience building or maintaining cross-platform Mobile Apps
 * Architecture & Design: Solid grasp of API design, web & mobile architecture, as well as good UX design.
 * Communication: Clear, pragmatic communicator who collaborates well with both engineers and non-engineers.

## Description

* Design & Build: Deliver robust, maintainable features across the stack (Scala/Play backend, React/AG-Grid frontend)
 * Mobile Migration: Define the path from Codename One to a JS-compatible framework (likely React Native), including architecture, incremental migration strategy, and performance/UX parity
 * Quality & Reliability: Champion code quality, testing, observability (metrics, logs, tracing), and performance across the stack
 * Team Growth: Mentor engineers, assist with hiring, onboarding, and capability development as the team scales.
 * Collaboration: Partner closely with the Desktop application development team to ensure feature compatibility and parity

Tech Stack

 * Backend: Scala, Play Framework, REST/JSON and gRPC
 * Frontend: React, TypeScript, AG-Grid
 * Mobile: Current app in CodenameOne, target migration to React Native (or similar JS-based cross-platform framework)
 * Tooling: Jenkins, GitLab, SonarQube, IntelliJ IDEA