Overview:

Connecting clients to markets – and talent to opportunity

With 4,300 employees and over 400,000 retail and institutional clients from more than 80 offices spread across five continents, we’re a Fortune-100, Nasdaq-listed provider, connecting 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, The StoneX Group is made up of four segments that offer endless potential for progression and growth.

Business Segment Overview – Payments: 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.

Position Purpose: This role exists to support the development and continuous improvement of the payment processing system. Working under the guidance of senior engineers, the Developer Intern contributes to building and maintaining features across trade execution, pricing, settlements and multi-currency payment flows. The position provides hands-on exposure to financial technology while helping the team deliver secure, compliant and efficient global transaction capabilities — and builds the technical foundation for a longer-term engineering career at StoneX

Key Responsibilities — Senior Staff Engineer

• Collaborate with business analysts, architects, product owners, and engineering teams to understand functional and non-functional requirements and translate them into scalable technical solutions
• Design, develop, and maintain robust backend services and applications using C#/.NET, following established architectural and engineering best practices
• Work with and contribute to Java-based services where required, with the ability to understand and troubleshoot existing Java codebases
• Design, develop, and maintain RESTful APIs, including API integration, authentication, error handling, performance, and versioning
• Design and optimize data access across MongoDB and PostgreSQL ensuring data integrity, performance and scalability
• Build and maintain event-driven and asynchronous integrations using technologies such as Apache Kafka and Azure Service Bus
• Write clean, maintainable, testable, and secure code with appropriate unit and integration test coverage
• Participate actively in solution design, technical discussions, code reviews and architectural decisions
• Use Git/GitHub effectively for source control, branching, pull requests and collaborative development
• Build, enhance, and maintain CI/CD pipelines using GitHub Actions and/or Azure DevOps, supporting automated build, test, deployment and release processes
• Containerize applications and services using Docker and apply containerization best practices for consistent deployment across environments
• Develop, deploy, and support applications and services hosted on Microsoft Azure, leveraging appropriate Azure services and monitoring capabilities
• Troubleshoot complex application and production issues across APIs, databases, messaging and integrations, performing root-cause analysis and implementing sustainable fixes
• Identify opportunities to improve application performance, reliability, scalability, security, and maintainability
• Participate actively in Agile ceremonies, including sprint planning, stand-ups, refinement, reviews, and retrospectives
• Leverage modern development and Generative AI tools such as GitHub Copilot/Claude Code to improve development productivity, debugging, refactoring and code quality

Minimum (Must-Haves)

• 7+ years of professional software development experience, with strong hands-on experience in backend development using C# and .NET
• Strong understanding of C#, .NET, OOP, SOLID principles, design patterns, asynchronous programming and backend application architecture
• Strong experience in designing, developing and integrating RESTful APIs and distributed backend services
• Hands-on experience with MongoDB and/or PostgreSQL, including data modelling, querying, indexing and performance optimization
• Practical experience with CI/CD pipelines, preferably using GitHub Actions and/or Azure DevOps
• Hands-on experience with Docker and containerized application development/deployment
• Experience developing or supporting applications and services on Microsoft Azure
• Experience with messaging or event-driven architectures using Apache Kafka, Azure Service Bus or similar technologies
• Strong understanding of software engineering fundamentals, including scalability, reliability, security, performance, testing, and maintainability
• Strong analytical and troubleshooting skills, with experience diagnosing complex issues across application, database, messaging, and integration layers
• Strong communication and collaboration skills with the ability to work effectively with developers, QA, business analysts, architects, and other stakeholders

Preferred (Nice-to-Haves)

• Working knowledge or hands-on exposure to Java, with the ability to understand, troubleshoot and contribute to Java-based backend services
• Experience with Lightstreamer or similar real-time messaging/streaming technologies
• Experience with multiple Azure services and cloud-native application patterns
• Experience implementing automated unit, integration and API testing within CI/CD pipelines
• Exposure to monitoring, logging, observability, and production-support practices for distributed applications
• Experience with Financial Services, particularly Payments, FX, Banking or transaction-processing systems
• Experience mentoring junior engineers and contributing to technical design and engineering standards
• Practical experience using GitHub Copilot/Claude Code or other Generative AI/agentic development tools for development, debugging, code reviews or automation

Education / Certification Requirements: 

• Bachelor’s degree in Computer Science/Engineering or related field

Working environment

• Hybrid (4 days from office)