Senior .NET Developer (Capital Markets)

Job Description Development is the largest discipline at Keystone AI. Our developers design, build, and release software products using a wide range of programming languages, frameworks, and technologies. Working closely with cross-functional project teams, our developers are adaptable problem-solvers with a client-oriented mindset. This role is available on a full-time employment contract (UoP) and requires the willingness to work from one of our offices in Kraków, Warszawa, or Gdańsk twice a week . Responsibilities Designs, estimates, and implements technical solutions for medium/high-complexity applications. Participates actively in all phases of the application development lifecycle. Collaborates with various project stakeholders to provide support in clarifying requirements, processes, architecture, and priorities. Recommends and promotes IT industry standards, tools, and engineering best practices (including DevOps) to deliver high-quality software solutions. Proposes improvements and escalates risks or issues related to development activities. Participates in code reviews and provides constructive feedback to development team members. Learns and applies new technologies, practices, and tools as appropriate to the project. Participates in internal and external technology communities, knowledge-sharing sessions, and industry events. Shares experience and technical knowledge gained from projects with colleagues. Qualifications 6+ years of experience in software development using Microsoft technologies. Experience working in Capital Markets, Trading, Equity Derivatives, or the broader Financial Services industry is required. Strong understanding of common programming paradigms (Object-Oriented Programming, Functional Programming, etc.). Strong familiarity with design and architectural patterns and clean code principles (e.g., SOLID, GoF). Proficient in C#, .NET 6/7/8 or .NET Core, ASP.NET Core, Entity Framework Core, Visual Studio or JetBrains Rider, and NuGet. Experience building RESTful APIs and distributed applications. Practical experience working with relational databases and SQL (e.g., SQL Server, PostgreSQL, Oracle). Good understanding of version control systems such as Git. Solid experience with unit testing and mocking frameworks (e.g., xUnit, NUnit, MSTest, Moq). Familiarity with communication protocols and standards such as HTTP, REST, JSON, TCP/IP, and messaging technologies. Experience with Agile methodologies (e.g., Scrum, Kanban). Knowledge of CI/CD tools and practices (e.g., Azure DevOps, GitHub Actions, Jenkins). Good problem-solving skills and analytical thinking. Excellent communication and teamwork abilities. Upper-intermediate or higher English proficiency. Company Description Technology is our how. And people are our why. For over two decades, we have been harnessing technology to drive meaningful change. By combining world-class engineering, industry expertise and a people-centric mindset, we consult and partner with leading brands from various industries to create dynamic platforms and intelligent digital experiences that drive innovation and transform businesses. From prototype to real-world impact - be part of a global shift by doing work that matters. Additional Information “For this position, the gross base salary starts with PLN 19 267 PLN Gross per month (full-time employment contract), determined using objective and gender-neutral criteria including skillset, experience and role responsibilities. Our benefits offering typically include private medical insurance, dental plan, and glasses reimbursement. The figure represents the initial remuneration we expect to offer for this role and does not limit the right to equal pay for women and men performing the same work or work of equal value. All remuneration and benefits decisions are based on non-discriminatory, gender-neutral criteria, and in accordance with the Polish Labour Code amendments implementing Directive on pay transparency, we do not request or consider candidates’ current or past remuneration during the recruitment process.” At Keystone AI, we’re committed to creating an open, inclusive, and respectful environment where everyone feels safe, valued, and empowered to be their best. We welcome applications from people of all backgrounds, experiences, and perspectives—because we know that inclusive teams help us deliver smarter, more innovative solutions for our customers. Hiring decisions are based on merit, skills, qualifications, and potential. If you need adjustments or support during the recruitment process, please let us know.