Senior C# Software Engineer Greenfield Platform | in Office

Senior C# Software Engineer| Payments | £140,000 | Greenfield Payments Platform | 3 Days in Office

Location: Central London Sector: Capital Markets / Global Fintech Infrastructure

The Mission:
Architecting a Global Financial Backbone

As our client accelerates its expansion as a Nasdaq-listed global financial platform, they are launching a high-priority initiative to build a greenfield, proprietary technology stack for their Capital Markets and Global Payments division. This is not a role for a "feature-developer" but for a seasoned software engineer who views back-end development as a craft. You will join a specialized squad tasked with creating a secure, robust, and differentiating payments ecosystem that serves as the primary gateway for major financial institutions and corporate clients worldwide.

In this role, your technical expertise will be the catalyst for the platform’s success. You will sit at the center of the design phase, moving beyond simple API creation to help architect a globally distributed system that prioritizes an automation-first Dev Ops approach. The challenge is significant: you will be responsible for engineering event-driven workflows and low-latency, high-throughput APIs that maintain absolute integrity under the pressure of global market volumes.

This position offers true technical sovereignty, working alongside the enterprise architecture stream to define organizational patterns that will dictate how the firm scales for years to come.

Beyond the code, you will act as a technical lighthouse within the squad. This involves not only mentoring junior developers but proactively identifying opportunities to refine the developer ecosystem to support a high frequency of change without any degradation in quality. You will bridge the gap between complex business outcomes and strategic technology delivery, ensuring that every service built aligns with the "big picture" of a rapidly evolving global market.

The Technical Bar

• Core Engineering
  :
  Expert proficiency in C#, .Net Core
  , and SQL
  , with a deep-seated focus on performance-first backend development.
• Distributed Design
  :
  Extensive experience in API design (HTTP/REST), micro-services architecture, and implementing data caching strategies for globally distributed systems.
• Cloud & Dev Ops
  :
  Professional experience with AWS and a mastery of the Modern SDLC
  , including DORA metrics
  , CI/CD automation
  , and BDD/TDD
  .
• Ecosystem Knowledge
  :
  Skilled in SQL Server
  , MongoDB
  , and Linux environments.
• Architectural Fluency
  :
  Mastery of Event-driven patterns,
  Pub/Sub
  , and Real-time/Websockets for high-availability systems.
• Professional Standards
  : A "shift-left" mindset regarding quality, taking full accountability for deliverables while enforcing SOLID principles.

• Greenfield Sovereignty
  :
  You are building a brand-new proprietary platform from scratch, avoiding the legacy "spaghetti code" common in bulge-bracket firms.
• Direct Business Proximity
  :
  You work as part of an agile "stream" aligned to the Capital Markets business technology function, ensuring your work has a visible, direct impact on revenue.
• High-Growth Culture
  :
  Enjoy the nimbleness of an adaptable and non-bureaucratic environment backed by the financial power of a Nasdaq-listed global leader.