Senior Backend Engineer (.NET) with Agentic Dev

Overview

Permanent, full-time, hybrid

Connecting clients to markets – and talent to opportunity.

With 5,400+ employees and over 80,000 institutional, commercial, and payments clients, we operate from more than 80 offices spread across six continents. As a Fortune 100, Nasdaq-listed provider, we connect clients to the global markets – focusing on innovation, human connection, and providing world-class products and services to all types of investors. 
 
Whether you want to forge a career connecting our retail clients to potential trading opportunities, or ingrain yourself in the world of institutional investing, StoneX Group is made up of four business segments that offer endless potential for progression and growth.

Business Segment Overview: A Swift-accredited service bureau and member, our Payments division provides NGOs, institutions and non-profits the ability to make a local difference, globally – with transparent pricing across 180+ countries and 140+ currencies. 

Responsibilities

Position Purpose: We are seeking a Senior Backend Engineer to design, build, and lead the evolution of high-impact backend systems powering business-critical applications across StoneX Payments.

This role is ideal for a highly experienced backend engineer who:

• Thrives on end-to-end ownership across the SDLC

• Influences technical direction across multiple squads

• Leads complex initiatives without formal people management

• Actively advances agentic development practices within engineering

You will operate as a technical authority within your domain - shaping backend architecture, raising engineering standards, and enabling teams to safely leverage AI-augmented development in a regulated financial environment.

Key Responsibilities will include:

1. Backend Architecture & System Design

• Design and evolve scalable backend systems using C# and .NET (ASP.NET Core, Web APIs).

• Define robust RESTful APIs and service contracts for frontend and downstream consumers.

• Contribute to domain architecture strategy and ensure alignment with platform principles.

• Lead complex technical initiatives spanning multiple squads.

• Drive improvements in system performance, reliability, observability, and data integrity.

• Champion clean architecture, modular design, and maintainable service boundaries.

You are expected to influence architecture beyond a single squad and elevate backend engineering standards across the domain.

2. Agentic Development Enablement (Cross-Team Scope)

A defining aspect of this role is structured adoption and standardization of agent-augmented engineering.

• Act as an advanced practitioner of AI-assisted development tools (e.g., Claude Code, Copilot Workspace, or equivalent).

• Design and refine backend workflows that effectively leverage agents for:

  • Refactoring legacy services

  • Automated test generation

  • Debugging and root cause analysis

  • Documentation improvement

  • Code modernization and dependency management

• Improve backend “agent-readiness” by driving:

  • Clear service boundaries

  • Strong unit and integration test coverage

  • Consistent naming and documentation standards

  • Reduction of unnecessary coupling

• Establish guardrails for reviewing and validating AI-generated code, including:

  • Architectural alignment

  • Security and compliance review

  • Performance considerations

• Share best practices and coach engineers on responsible AI-assisted development.

• Partner with Lead and Principle engineers to align with broader agentic engineering standards.

Your focus is not experimentation alone - but systematic improvements in code quality, maintainability, and engineering throughput across multiple teams.

3. End-to-End Delivery & Technical Execution

• Participate across the full SDLC — from story refinement and design through implementation, deployment, and production support.

• Write high-quality, testable, production-grade backend code.

• Lead technical breakdown of large features and complex initiatives.

• Ensure strong automated testing (unit, integration, contract tests) and CI/CD hygiene.

• Drive technical risk identification and mitigation early in the lifecycle.

• Support incident resolution and root cause analysis in production systems.

4. Technical Leadership Without Direct Management

• Serve as a senior technical reference point for backend engineers.

• Conduct rigorous code reviews and architectural deep dives.

• Mentor engineers on backend design patterns, distributed systems principles, and clean coding standards.

• Facilitate architecture discussions and influence technical decisions across squads.

• Contribute to internal standards, documentation, and reusable backend patterns.

This role leads through influence, expertise, and technical credibility rather than formal people management.

Qualifications

To land this role you will need:

Core Backend Engineering

• 5+ years of professional software engineering experience with strong backend focus.

• Deep expertise in C# and .NET (ASP.NET Core, Web APIs).

• Strong experience designing and maintaining RESTful services and service-oriented architectures.

• Solid understanding of clean architecture, SOLID principles, and scalable design patterns.

• Experience with relational and/or NoSQL databases and performance optimization.

• Strong grounding in CI/CD, version control (Git), and cloud-native development.

• Experience with Azure cloud services and containerization.

• Exposure to event-driven architectures, messaging, and distributed systems.

• Familiarity with infrastructure-as-code and observability tooling.

Agentic Development Capabilities

• Hands-on experience using AI-assisted development tools (e.g., Claude Code, GitHub Copilot, Copilot Workspace, or equivalent).

• Ability to evaluate and validate AI-generated backend code for correctness, maintainability, and security.

• Understanding of how architecture quality, modularity, and test coverage influence agent effectiveness.

• Experience improving legacy systems in ways that increase automation and agent compatibility.

• Pragmatic mindset balancing acceleration with governance and financial system rigor.

Collaboration & Influence

• Strong cross-functional collaboration skills with Product, QA, frontend engineers, and DevOps.

• Experience leading technical initiatives without direct people management.

• Clear communicator capable of articulating architectural trade-offs and technical risks.

• Comfortable operating in Agile, distributed environments.

Education / Certification Requirements: 

• Bachelor’s degree in information technology.

Working environment: 

• Hybrid 4-days in office with private parking for employees.