Senior C# Developer

Contract Opportunity | Tier 1 Investment Bank | Canary Wharf Overview Our client, a Tier 1 Investment Bank based in Canary Wharf, is seeking an experienced C# Developer to join a strategic application modernisation…

Inside IR35 Hybrid IT
Pay rate £400 – £416/day
Contract type Contract
Posted 15 September 2026

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About this contract

Inside IR35

Contract Opportunity | Tier 1 Investment Bank | Canary Wharf

Overview

Our client, a Tier 1 Investment Bank based in Canary Wharf, is seeking an experienced C# Developer to join a strategic application modernisation programme. This role sits within a technology team responsible for evolving critical business applications, supporting a transition from legacy desktop solutions to modern web-based and cloud-enabled platforms.

The successful candidate will work across the full software development lifecycle, contributing to the enhancement of existing applications while helping shape the future-state architecture.

Key Information

Role: Senior C# Developer
Location: Canary Wharf, London (Hybrid Working)
Contract Length: 6 Months Initial Contract
Rate: £416 per day (Inside IR35)
Start Date: ASAP

The Programme

This role forms part of a wider transformation initiative focused on:

Modernising legacy desktop applications
Migrating technology platforms from on-premise infrastructure to Azure
Supporting the transition from desktop-based solutions to web technologies
Improving application performance, maintainability and scalability
Delivering new functionality aligned to business and regulatory requirementsThe successful contractor will work closely with development teams, business stakeholders and architecture functions to deliver high-quality software solutions within a complex enterprise environment.

Key Responsibilities

Develop and maintain enterprise-grade applications using C#
Enhance and support existing WPF and WinForms applications
Contribute to the migration of desktop applications towards web-based architectures
Build and integrate APIs and backend services
Write efficient SQL queries and stored procedures
Collaborate with business analysts, architects and end users to understand requirements
Participate in code reviews and promote development best practices
Troubleshoot production issues and contribute to continuous improvement initiatives
Support the adoption of Azure technologies as part of the broader cloud transformation strategy

Required Skills & Experience

Essential

Strong commercial experience developing applications using C#/.NET
Proven expertise with WPF or Winforms
Strong SQL or Oracle development skills
Understanding of software design principles and development best practices
Experience working within complex enterprise environments
Experience working with Azure

Desirable

Experience with JavaScript
Exposure to React
Experience contributing to application modernisation programmes
Knowledge of Azure cloud technologies
Experience within Financial Services, Investment Banking or Capital Markets environments

Personal Attributes

Strong analytical and problem-solving skills
Excellent communication and stakeholder management abilities
Ability to work independently in a fast-paced environment
Collaborative mindset and willingness to mentor junior developers
Comfortable balancing support of legacy systems alongside modernisation initiatives

GCS is acting as an Employment Business in relation to this vacancy

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