Mid Fullstack Engineer (Dotnet & React) with Agentic Dev at StoneX Group

Krakow, Lesser Poland Voivodeship, Poland -

Full Time

Start Date

Immediate

Expiry Date

15 Jul, 26

Salary

0.0

Posted On

16 Apr, 26

Experience

2 year(s) or above

Remote Job

Yes

Telecommute

Yes

Sponsor Visa

Skills

C#, .NET, ASP.NET Core, React, TypeScript, RESTful APIs, SQL Server, Git, CI/CD, AI-assisted development, GitHub Copilot, Claude Code, Unit testing, Integration testing, Software engineering, Fullstack development

Industry

Financial Services

Description

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 Mid Fullstack Engineer to design, build, and enhance scalable, business-critical applications across backend and frontend layers. This role is ideal for an engineer who: Works confidently across C#/.NET backend and React frontend Owns features end-to-end with minimal supervision Raises quality and engineering discipline within their squad Effectively leverages AI-assisted development tools to improve productivity and maintainability As a Mid Fullstack Engineer, you are a strong, autonomous contributor and an emerging technical leader within your team. You combine solid fullstack expertise with disciplined engineering practices and pragmatic adoption of agentic development workflows. Key Responsibilities will include: 1. Fullstack Development & Feature Ownership Contribute across the full software development lifecycle — from refinement and technical design through implementation, testing, deployment, and production support. Build and maintain backend services using C# and .NET (ASP.NET Core, Web APIs). Develop modern frontend components using React and TypeScript. Design and consume RESTful APIs, ensuring clear and stable contracts between frontend and backend. Work with databases and data models to ensure performance, integrity, and reliability. Own medium-sized features end-to-end across the stack. Write clean, modular, and testable code with appropriate unit and integration tests. Participate actively in code reviews and architectural discussions. You are expected to deliver independently while contributing to continuous improvement of the overall system. 2. Agentic Development Application (Squad-Level Optimization) Agent-augmented engineering is an expected capability at this level. Actively use AI-assisted development tools (e.g., Claude Code, GitHub Copilot, or equivalent) to: Accelerate feature implementation across backend and frontend Generate and improve unit/integration tests Refactor components and services Assist in debugging and issue investigation Improve documentation and code clarity Critically evaluate and validate AI-generated code before committing it to production. Ensure AI-assisted output aligns with: Established architectural patterns Security and compliance standards Maintainability expectations Contribute to making the codebase more “agent-ready” by: Improving modularity and separation of concerns Strengthening TypeScript typing and API contracts Increasing automated test coverage Reducing unnecessary coupling Share effective AI-assisted development practices with teammates. You are an advanced practitioner of agentic tools who improves how your squad leverages them safely and effectively. 3. Delivery & Collaboration Collaborate closely with Product, QA, DevOps, and senior engineers to deliver high-quality features. Participate in story refinement, estimation, and technical breakdown. Identify and surface technical risks early. Support production systems through debugging and root cause analysis. Contribute to CI/CD pipelines and ensure reliable deployments. You help strengthen delivery predictability and engineering quality within your team. 4. Technical Growth & Influence Demonstrate strong ownership and accountability across frontend and backend components. Provide thoughtful, constructive code reviews that improve quality. Mentor junior engineers informally where appropriate. Continuously improve your fullstack expertise and understanding of cloud-native patterns. Stay current with evolving .NET, React, Azure, and AI-assisted development practices. You are progressing toward broader architectural influence and cross-team impact (Senior trajectory). Qualifications To land this role you will need: Fullstack Engineering 3–6 years of professional software engineering experience with meaningful fullstack exposure. Strong working knowledge of C# and .NET (ASP.NET Core, Web APIs). Solid experience building frontend applications with React and TypeScript. Experience designing and consuming RESTful services. Familiarity with relational databases (e.g., SQL Server) and basic data modeling. Understanding of clean code principles, maintainable design, and automated testing. Experience using Git, CI/CD pipelines, and modern development workflows. Agentic Development Capabilities Hands-on experience using AI-assisted coding tools (e.g., GitHub Copilot, Claude Code, or equivalent). Ability to evaluate AI-generated backend and frontend code critically. Understanding of how modular design, strong typing, documentation, and test coverage improve AI tool effectiveness. Pragmatic mindset — using AI to accelerate delivery without compromising quality or security. Collaboration & Mindset Strong team collaboration and communication skills. Ability to take feedback constructively and improve continuously. Growth mindset with ambition to expand technical ownership and cross-stack expertise. Comfortable working in Agile, cross-functional environments. Nice to Have Exposure to Azure or other cloud platforms. Experience with Docker, microservices, or distributed systems. Familiarity with CI/CD pipelines and automated testing frameworks. Experience contributing to shared component libraries or frontend standards. Interest or exposure to financial services, payments, or trading platforms. Working environment: Hybrid 4-days in office with private parking for employees. #LI-Hybrid #LI-DK1

Responsibilities

The Mid Fullstack Engineer will design, build, and maintain scalable applications using C#/.NET and React while owning features end-to-end. The role also involves leveraging AI-assisted development tools to optimize squad-level productivity and code quality.