Senior Software .NET Engineer

Overview

Permanent, full-time, hybrid

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: 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. 

Technology Ecosystem:

• Back End: C#, .NET

• Database: SQL Server

• Cloud: Azure

Responsibilities

Position Purpose: StoneX Payments is looking for a Senior Software Engineer to design, develop and implement software applications that make up key components of our platforms. You will deliver high-quality software that is aligned with customer needs and business goals. You will be expected to set standards in a highly modernize and distributed environment.

You will be responsible for the technical excellence and approach taken by less experienced team members, including providing guidance and oversight, planning and estimation, analyzing software performance and configuration systems, peer code reviews and documentation, and the deployment and integration of new software from technology standards you set. You will collaborate with product owners in an agile scrum to scope, develop and deploy solutions, continuously iterating to ensure that new features are adding value to our customers.

You are expected to conduct design and code reviews within the engineering team and vetting designs across your teams with business initiatives. You are expected to get into the details of our solutions, lead implementation, and take ownership of the team’s output.

Come help us develop the next-generation payments platform! The ideal candidate is passionate about growing their skills and building complex distributed systems.

Primary duties will include: 

• Execute on the software development life cycle (SDLC) for the team including estimating, analysis, code design, development, testing, debugging, and maintenance.

• Implement engineering standards, best practices, and quality assurance procedures.

• Work closely with product owners to understand product requirements and translate them into technical stories.

• Provide technical expertise and insight to analyze complex requirements and break down features and initiatives into tasks.

• Take responsibility for the quality of the applications as well as its alignment with technology and product goals.

• Review and give constructive feedback on code.

• Identify recurring issues and opportunities to improve engineering process and coding standards.

• Lead the execution of software solutions along with monitoring and supporting tools to ensure the software works well in the operating environment.

• Actively participate in strategic implementation regarding technology solutions and platform architecture

• Mentor and grow less experienced engineers.

• Forward thinking on modern technology and the payments industry.

Agentic Development Leadership:

This is the major differentiator of the role.

• Introduce, design, and operationalize agent-based engineering workflows across the SDLC.

• Use tools such as Claude Code, capable of repository-wide reasoning, automated refactoring, debugging, and commit generation to accelerate engineering throughput.

• Build “agent-ready” codebases through modular design, clean documentation, and comprehensive test coverage — key enablers of successful agentic development.

• Actively contribute to and/or lead the new agentic development team for Payments (e.g., new wallet solution POC).

• Evaluate AI-generated code for quality, correctness, architectural alignment, and security.

• Develop internal best practices, training materials, and standards for agent-accelerated engineering.

Qualifications

To land this role you will need:

• 5+ years software engineering experience, primarily Back-End or Full-Stack.

• Experience with .NET and Cloud platforms (Azure/AWS/GCP).

• Experience working with Docker, .NET 6+, C#.

• Experience designing and writing robust software for highly scalable, low-latency, event driven, distributed platforms.

• Strong experience with object-oriented programming and design, including C# or any other programming languages.

• Experience designing, implementing, and integrating with RESTful and gRPC APIs.

• Experience with modern architectures and practices including microservices, cloud computing, micro frontends, and domain driven design.

• Experience with financial products, specifically payments.

• Experience with Jira and Confluence.

• Able to work in a positive team culture with a strong sense of accountability and collaboration.

• Able to balance incoming requirements with a focus on tactical execution.

• Excellent coding skillset and peer code review.

• Excellent verbal and written communication skills.

• Excellent analytical and problem-solving skills.

• Excellent skills working in a distributed Lean Agile Scrum Team.

• Deep understanding of modern cloud native technology with microservice/microsite design patterns.

What makes you stand out: 

• Experience in SaaS, Payments, FinTech, or E:commerce.

• Experience with IaC, specifically Terraform.

• Experience with microservice design pattern, specifically Twelve-Factor.

• Experience with document databases.

• Experience working with VueJs/React, and Postgres.

Agentic Development Skills:

(What makes this role unique)

• Hands-on experience with agentic development tools such as Claude Code, Copilot Workspace, or equivalent.

• Ability to orchestrate multi-agent workflows (refactoring, debugging, dependency updates, code generation).

• Deep understanding of how design quality affects agent output (modularity, documentation, test coverage).

• Experience evaluating and validating AI-generated code.

• Ability to build frameworks, patterns, and tooling for agent-powered engineering at scale.

Working environment:

• FTE (UoP).

• Hybrid at ul. Mogilska 35 – we have private parking for employees.