Software Engineer

Harrington Starr; City Of London; On-site; GBP 60,000 - 80,000; Full time

Job summary

Harrington Starr is seeking an experienced Software Engineer to join a high-performing engineering team within a fast-growing fintech in London. The role involves developing and enhancing core trading and treasury systems and contributes significantly to the company's technology evolution.

The ideal candidate will have 5+ years of C#/.NET experience and knowledge of cloud-native solutions. This position offers a hybrid working model with flexibility, making it a unique opportunity for those looking to innovate in financial technology.

Qualifications

• 5+ years’ experience working with C#/.NET.
• Experience developing front and middle office systems.
• Experience with cloud-native solutions (Azure or AWS).

Responsibilities

• Develop and maintain software across the full stack.
• Contribute to architecture and design decisions.
• Support, optimise, and maintain production code.

Skills

C#/.NET

Cloud-native solutions

Event-driven architectures

Microservices architectures

Job description

Overview

Harrington Starr has partnered with a fast-growing fintech that’s transforming how businesses manage foreign exchange and treasury operations. Their technology enables clients to access institutional-grade execution, automate manual workflows, and gain greater transparency across their financial processes. Handling billions in transactions each year, they continue to expand their product offering and deliver cutting-edge solutions that help clients manage risk more effectively.

The Role

This is an excellent opportunity for an experienced Software Engineer — ideally with a background in financial technology or FX — to join a high-performing engineering team within a scaling fintech. You’ll be instrumental in developing and enhancing the company’s core trading and treasury systems, building new features, improving performance, and driving integration across their technology stack.

Key Responsibilities

• Develop and maintain software across the full stack
• Contribute to architecture and design decisions
• Support, optimise, and maintain production code
• Research and integrate new technologies
• Foster a culture of engineering excellence and continuous improvement

Key Requirements

• 5+ years’ experience working with C#/.NET
• Experience developing front and middle office systems
• Experience with cloud-native solutions (Azure or AWS)
• Knowledge of event-driven, microservices architectures
• Full SDLC experience — from design through delivery and support
• Join a fast-scaling fintech building next-generation financial technology
• Work on complex, high-impact systems handling large-scale transactions
• Collaborative, innovative, and growth-oriented team culture
• Hybrid working model with flexibility and autonomy