Senior .NET Developer

🏢 Summary: Senior .NET Developer role focused on building and enhancing a cloud-native embedded finance platform in a regulated FinTech environment. The position involves designing, developing, and deploying scalable, secure features using a modern tech stack while ensuring high performance and reliability in production. You will work across backend and frontend technologies, contributing to CI/CD, cloud infrastructure, and event-driven systems. 🗂️ Requirements: 5+ years of software development experience, Strong OOP and system design skills, Hands-on experience with .NET and C#, Hands-on experience with Angular, Understanding of software testing concepts, Experience with cloud-native architectures, Experience with CI/CD and DevOps practices, Experience with relational databases, Experience with NoSQL databases, Knowledge of performance, security, and availability principles, Experience in FinTech, payments, banking, or regulated environments, Upper-Intermediate English or higher 📃 Skills: C#, .NET, Angular, AWS, CI/CD, Docker, Kubernetes, Kafka, RabbitMQ, Datadog, SQL, NoSQL, OOP, DDD 🏢 Description: Looking to take your .NET expertise to the next level while working on high-impact FinTech solutions? This role offers the chance to contribute to scalable, cloud-native systems that empower thousands of businesses worldwide. We’re seeking a Senior .NET Developer to join our team, collaborating with talented engineers, product managers, and designers to deliver innovative financial technology. At Sigma Software, we work with some of the most forward-thinking companies in the industry. This opportunity will let you grow professionally while making a tangible difference in a fast-paced, regulated environment. Customer Our customer is a leading FinTech company providing embedded financing solutions for platforms and marketplaces. Their mission is to enable businesses to offer flexible credit products to customers, helping SMEs access funding quickly and efficiently. The customer is recognized for innovation in embedded finance, serving thousands of businesses globally and partnering with major platforms. They operate in a regulated environment with a strong focus on scalability, performance, and security. Project The project involves enhancing and expanding customer’s embedded finance platform, which integrates directly into partner services to deliver fast, flexible funding to SMEs. You’ll work on a modern tech stack, building features that improve customer and partner experiences while ensuring reliability in production. Key Technologies: C#, .NET Core, Angular 18, AWS, CI/CD, Docker/Kubernetes, Kafka/RabbitMQ, Datadog, relational & NoSQL databases. Responsibilities Design, build, and deliver features and projects across C#, .NET Core, and Angular stack Write clean, maintainable, and well-tested code (unit/integration/e2e) Take ownership of features from requirements breakdown to deployment Deploy and monitor services in AWS cloud-native environments Handle production issues and incidents with accountability Collaborate with Product, Design, and Engineering teams in Agile practices Contribute to continuous improvement of systems and processes Requirements 5+ years of experience in software development with strong OOP and system design skills Solid hands-on experience with .NET (C#) and Angular Understanding of software testing concepts and practices Expertise in cloud-native and DevOps practices (CI/CD, automation, monitoring) Experience with relational and NoSQL databases Knowledge of non-functional requirements (performance, security, availability) Proven experience in FinTech, payments, banking, or regulated financial environments Upper-Intermediate English level or higher Will be a plus Experience with Docker/Kubernetes Familiarity with event-driven architectures (Kafka, RabbitMQ) Proficiency with observability tools (Datadog or similar) Knowledge of domain-driven design (DDD) and complex domain modeling Personal profile Growth mindset, curiosity, and proactivity Strong problem-solving skills balancing complexity and simplicity Feedback-oriented, open to giving and receiving constructive input Ownership & accountability in delivering commitments Team player with strong collaboration skills Adaptability to changing priorities Excellent communication skills across disciplines

🏢 Summary: Senior .NET Developer role focused on designing, developing, and maintaining critical backend applications within a secure, large-scale financial enterprise environment. The position involves contributing to architectural decisions and delivering robust solutions that support complex financial operations. Ideal for a senior engineer seeking technical autonomy and impact in a stable yet modern setting. 🗂️ Requirements: Senior-level experience in .NET development, Proven experience designing backend applications, Experience developing and maintaining enterprise-grade systems, Ability to contribute to software architecture and technical design, Experience working in secure, large-scale environments, Strong understanding of robust engineering practices 📃 Skills: .NET, C#, Backend, Architecture, Enterprise, FinancialSystems 🏢 Description: Are you a seasoned software engineer looking to drive impactful backend solutions within a secure, large-scale enterprise environment? A leading international financial institution is seeking a Senior .NET Developer to join a highly specialized engineering team. In this role, you will play a pivotal part in designing, developing, and maintaining critical applications that support sophisticated financial operations. This is an exceptional opportunity for a senior professional who thrives on technical autonomy, values robust engineering practices, and is looking for a stable yet modern environment where their architectural input truly matters.

🏢 Summary: Senior .NET Developer role focused on building and maintaining secure, high-performance online banking solutions in a hybrid work model. The position involves developing new backend features, optimizing databases, and managing containerized applications in an Agile, distributed environment. The role also includes ensuring code quality, supporting production systems, and contributing to secure payment functionalities. 🗂️ Requirements: Minimum 4 years of experience in IT systems development, Strong hands-on experience with .NET, Strong knowledge of PostgreSQL, Strong knowledge of MS SQL, Experience with Docker, Experience with Kubernetes, Practical understanding of Agile methodology, Ability to develop new features and maintain existing systems, Ability to work independently in distributed teams 📃 Skills: .NET, C#, PostgreSQL, MS SQL, SQL, Docker, Kubernetes, Agile, Elixir, Sorbnet 🏢 Description: Innovate online banking and join the team as a Senior .NET Developer! Warsaw-based opportunity with hybrid work model (2 times in the office/month). As a Senior .NET Developer , you will be working for our client, one of the leaders in online banking, supporting the development and maintenance of secure, high-performance financial solutions. You’ll be contributing to a team responsible for building and enhancing banking functionalities, ensuring reliability and innovation. Working in a distributed Agile environment, you’ll play a key role in both implementing complex backend logic and actively collaborating with cross-functional teams. Your main responsibilities: Design and develop new features in .NET 8 Implement and optimize SQL-based data access Build and maintain containerized applications using Docker and Kubernetes Collaborate with distributed teams in an Agile environment Participate in the development of secure payment solutions Share knowledge and support less experienced team members Ensure code quality through code reviews and testing Maintain existing functionalities and resolve production issues Manage your own time and responsibilities while working remotely You're ideal for this role if you have: Strong experience in developing IT systems (min. 4 years of experience) Solid hands-on experience with .NET Strong knowledge of PostgreSQL and MS SQL Practical understanding of Agile software development Excellent communication and collaboration skills in distributed teams Ability to work independently and manage your time effectively Experience in developing new features and maintaining existing ones A passion for software development and continuous learning Experience with Docker and Kubernetes Nice to have: Knowledge of banking domain such as payments and transactions (e.g. Elixir, Sorbnet)

🏢 Summary: Senior Software Engineer role focused on developing and maintaining a complex enterprise .NET platform, combining backend development, production troubleshooting, and performance optimization. The position involves working on identity-related systems and improving architecture, reliability, and code quality within a large-scale environment. The engineer will contribute to technical decisions and future platform evolution. 🗂️ Requirements: 5+ years commercial experience with C# and .NET, Strong knowledge of ASP.NET Core, Experience with asynchronous programming, Experience with dependency injection, Hands-on experience with Entity Framework Core, Strong understanding of SQL Server, Experience with query optimization, Experience with OAuth2, Experience with OpenID Connect, Experience with JWT, Experience supporting and troubleshooting production systems, Fluent English 📃 Skills: C#, .NET, ASP.NET, EntityFramework, SQLServer, OAuth2, OpenIDConnect, JWT, IdentityServer, Duende, ActiveDirectory, AzureAD, MicrosoftGraph, Quartz.NET, SignalR, Playwright, AzureDevOps, CI/CD 🏢 Description: We are looking for an experienced Senior Software Engineer to develop and maintain a complex enterprise .NET platform used by global organizations. This role combines backend development , production troubleshooting , performance optimization , and work on identity-related systems . 💼 Responsibilities: Design, develop, and maintain backend services built with C# and .NET Investigate and resolve complex production issues and customer-reported problems Optimize application performance, database queries, and system reliability Collaborate with Product, Support, and Engineering teams on technical solutions Improve architecture, code quality, and engineering standards Participate in technical discussions and contribute to future platform development ✅ Requirements: 5+ years of commercial experience with C# and .NET Strong knowledge of ASP.NET Core and modern .NET applications Experience with asynchronous programming and dependency injection Hands-on experience with Entity Framework Core Good understanding of SQL Server, query optimization, and database performance Experience with OAuth2, OpenID Connect, JWT Experience supporting and troubleshooting production systems Fluent English communication skills 🌟Nice to have: Experience with IdentityServer / Duende IdentityServer Understanding of Active Directory, Azure AD or Microsoft Graph Hands-on experience with Quartz.NET or similar scheduling frameworks Familiarity with SignalR, Playwright, Azure DevOps and CI/CD pipelines 🎁 We offer: Work on a mature enterprise product used globally Influence technical decisions and platform evolution Private healthcare Life insurance Multisport Opportunity to work with modern .NET technologies and large-scale systems

🏢 Summary: Senior .NET Developer role focused on building and enhancing distributed microservices for digital banking systems in a European financial environment. The position involves designing scalable, high-quality solutions using C# and .NET, implementing asynchronous communication, and ensuring robust automated testing practices. Remote-first model with collaboration on complex financial platforms. 🗂️ Requirements: 5+ years of experience in C# and .NET development, Strong experience with microservices architecture, Knowledge of CQRS, REST, OOP, EventSourcing, Experience with RabbitMQ or Kafka, Experience with NoSQL and relational databases, Experience with automated testing (unit, integration, contract), Knowledge of DomainDrivenDesign principles, Understanding of BPMS workflows, Experience with Git, Good command of Polish, Legal right to work in the EU 📃 Skills: C#, .NET, Microservices, CQRS, REST, OOP, EventSourcing, RabbitMQ, Kafka, Git, NoSQL, SQL, Docker, Testcontainers, Pact, DomainDrivenDesign, BPMS 🏢 Description: Unleash innovation — revolutionize financial systems with expert .NET development! Wroclaw-based opportunity with remote work model (5 remote days per week). As a Senior .NET Developer , you will be working for our client, a leading financial organization committed to transforming the digital banking experience. You’ll contribute to building and enhancing distributed microservices that enable seamless financial operations across Europe, driving innovation and operational excellence. Your main responsibilities: Develop and maintain scalable, high-quality microservices using C# and .NET technologies following Domain-Driven Design principles. Design and implement asynchronous communication patterns with RabbitMQ or Kafka to ensure system robustness. Collaborate with cross-functional teams to create automated tests, including unit, integration, and contract tests, utilizing Docker, Testcontainers, and Pact. Optimize code for performance, scalability, and reliability, adhering to Clean Code standards. Implement RESTful APIs and work with NoSQL and relational databases for effective data management. Contribute to the continuous improvement of development processes and best practices. Engage proactively in team collaboration, sharing knowledge and solving complex technical challenges. You're ideal for this role if you have: Minimum of 5 years of experience in C# and .NET development in a senior role. Understanding of workflows in BPMS platforms. Strong knowledge of microservices architecture, CQRS, REST, OOP, and Event Sourcing. Practical experience with asynchronous messaging (RabbitMQ/Kafka), Git, NoSQL databases, and relational databases. Familiarity with automated testing frameworks, including unit, integration, and contract testing. Good understanding of Domain-Driven Design (DDD) principles and clean code practices. Excellent team collaboration skills and a responsible, engaged work attitude. It is a strong plus if you have: Experience with Polish language communication skills. Knowledge of automated testing tools and frameworks. Language Required for the role: Polish: Good command Eligibility for the role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior .NET + Angular Developer role focused on building and modernizing cloud-native financial systems using containerized microservices. The position involves designing scalable backend services, dynamic frontends, and leading Kubernetes-based deployments within a DevOps-driven environment. You will contribute to migrating legacy systems to a modern, resilient architecture with strong emphasis on clean code and automation. 🗂️ Requirements: 5+ years of experience in software engineering, Strong mastery of .NET (C#), Strong experience with Angular (v12+), Practical experience with Kubernetes, Experience building and running containerized applications, Proficiency in SQL Server or relational databases, Experience with database schema design and performance tuning, Knowledge of CI/CD practices, Understanding of TDD and SOLID principles, Fluent professional English 📃 Skills: .NET, C#, Angular, Kubernetes, SQL, SQLServer, CI/CD, TDD, SOLID, Azure, AWS, EKS, AKS, Kafka, Helm, Terraform, Microservices, Docker 🏢 Description: The Opportunity We are representing an established international financial institution currently undergoing a massive shift toward cloud-native architecture. While many firms talk about "digital transformation," this team is actively dismantling legacy monoliths and rebuilding them as high-performance, containerized microservices. We are looking for a Senior .NET + Angular Developer who doesn't just "use" Kubernetes but understands how to build and scale applications within a modern orchestration ecosystem. This is a role for an engineer who values clean code, architectural integrity, and the power of automated, scalable infrastructure. Your Impact Architect & Build: Design and develop robust backend services using .NET 8/Core and dynamic, responsive frontends in Angular. Cloud-Native Excellence: Take a lead role in deploying and managing services within Kubernetes , ensuring our applications are resilient, observable, and scalable. Database Engineering: Design efficient schemas and optimize complex queries within SQL environments to handle high-frequency financial data. Modernize the Stack: Actively participate in the migration of services to a containerized environment, advocating for best practices in CI/CD and DevOps. Collaborate: Work within a cross-functional team of high-caliber engineers, participating in deep-dive code reviews and architectural workshops. Your Technical Profile The Core: Extensive experience (5+ years) in software engineering with a strong mastery of .NET (C#) and Angular (v12+). The K8s Edge: Proven experience working with Kubernetes . You should be comfortable with pods, services, deployments, and understanding how your code behaves in a containerized environment. Data Mastery: Strong proficiency in SQL Server or similar relational databases, including performance tuning and schema design. Quality First: A mindset focused on TDD, Clean Code, and SOLID principles. Communication: Fluent professional English (written and spoken) is essential for collaboration with our global teams. Preferred (Nice-to-Have) Experience with Azure or AWS (EKS/AKS). Knowledge of Kafka or other message brokers for event-driven architecture. Familiarity with Helm charts or Terraform (IaC). What’s in it for You? Hybrid Flexibility: Work from the comfort of your home anywhere in Poland, with only two scheduled visits per month to our modern hub in Łódź for team integration and high-level strategy sessions. Premium Tech Stack: No "maintenance only" projects. You will work on greenfield features and modern cloud migrations. Stability & Growth: The security of an established enterprise with the agile mindset of a tech-forward team. Streamlined Recruitment: A transparent, technical process that respects your time.

🏢 Summary: Senior .NET Developer role focused on designing, extending, and modernising critical banking and securities systems in a fully remote B2B model. The position involves full-stack development, system integration, and cloud scaling within distributed, business-critical environments. The role requires close collaboration with business stakeholders and ownership of end-to-end application delivery. 🗂️ Requirements: 5+ years experience as .NET / C# Developer, Experience in banking or investment banking sector, Full-stack development experience, Knowledge of SOLID design principles, Experience with document-based databases, Experience with event-driven messaging frameworks, Experience with unit and integration testing, End-to-end application development experience, Ability to work during UK business hours, Based in Poland 📃 Skills: .NET, C#, MongoDB, SOLID, Messaging, UnitTesting, IntegrationTesting, Docker, Kubernetes, Cloud 🏢 Description: Work model: 100% remote (candidates must be based in Poland) Contract type: B2B Industry: Banking / Investment Banking We are looking for an experienced Senior .NET Developer to join a distributed engineering team working on critical banking systems. The role focuses on extending and modernising applications used across securities and banking operations, with a strong emphasis on system design, scalability, and cloud transformation. You will work end-to-end on business-critical systems, closely collaborating with Business Analysts, without a separate QA team. A solid background in banking or financial services is essential. Main Responsibilities: Design, develop, and extend .NET-based systems supporting multiple banking entities Contribute to the integration of securities and core banking platforms Support and enhance a portfolio of ~17 applications across product control and risk management Work with an in-house development framework in a full-stack capacity Participate in scaling applications for cloud-based, containerized environments Collaborate closely with business stakeholders to deliver robust solutions Ensure high code quality through unit and integration testing Key Requirements: 5+ years of professional experience as a .NET / C# Developer Hands-on experience in the banking or investment banking sector (mandatory) Full-stack development experience (backend-focused, frontend included) Strong understanding and practical application of SOLID design principles Experience with document-based databases (e.g. MongoDB) Experience with event-driven / event-based messaging frameworks Solid knowledge of unit and integration testing Experience working end-to-end on applications (development, testing, support) Ability to work independently in a fast-paced, regulated environment Availability during UK business hours Nice to Have: Experience with cloud platforms and application migration to cloud Experience with container technologies (e.g. Docker, Kubernetes) Exposure to systems such as Murex or large in-house banking platforms Background in securities, risk, or product control systems Other Details: This role is 100% remote with candidates required to be located in Poland. The contract is on a B2B basis within the banking and investment banking industry.

🏢 Summary: Senior .NET Developer role focused on designing, extending, and modernizing critical banking systems within securities and core banking domains. The position involves full-stack development, system integration, and cloud scaling in a distributed team without a separate QA function. Work includes end-to-end ownership of business-critical applications in a regulated investment banking environment. 🗂️ Requirements: 5+ years experience with .NET and C#, Hands-on experience in banking or investment banking, Full-stack development experience, Strong knowledge of SOLID principles, Experience with document-based databases, Experience with event-driven messaging frameworks, Knowledge of unit and integration testing, End-to-end application development experience, Ability to work independently in regulated environments, Availability during UK business hours, Poland-based residency 📃 Skills: .NET, C#, MongoDB, SQL, REST, Microservices, Docker, Kubernetes, Azure, UnitTesting, IntegrationTesting, EventDriven, Git 🏢 Description: Work model: 100% remote (candidates must be based in Poland) Contract type: B2B Industry: Banking / Investment Banking We are looking for an experienced Senior .NET Developer to join a distributed engineering team working on critical banking systems. The role focuses on extending and modernising applications used across securities and banking operations, with a strong emphasis on system design, scalability, and cloud transformation. You will work end-to-end on business-critical systems, closely collaborating with Business Analysts, without a separate QA team. A solid background in banking or financial services is essential. Main Responsibilities: Design, develop, and extend .NET-based systems supporting multiple banking entities Contribute to the integration of securities and core banking platforms Support and enhance a portfolio of ~17 applications across product control and risk management Work with an in-house development framework in a full-stack capacity Participate in scaling applications for cloud-based, containerized environments Collaborate closely with business stakeholders to deliver robust solutions Ensure high code quality through unit and integration testing Key Requirements: 5+ years of professional experience as a .NET / C# Developer Hands-on experience in the banking or investment banking sector (mandatory) Full-stack development experience (backend-focused, frontend included) Strong understanding and practical application of SOLID design principles Experience with document-based databases (e.g. MongoDB) Experience with event-driven / event-based messaging frameworks Solid knowledge of unit and integration testing Experience working end-to-end on applications (development, testing, support) Ability to work independently in a fast-paced, regulated environment Availability during UK business hours Nice to Have: Experience with cloud platforms and application migration to cloud Experience with container technologies (e.g. Docker, Kubernetes) Exposure to systems such as Murex or large in-house banking platforms Background in securities, risk, or product control systems Other Details: This role is 100% remote with candidates required to be located in Poland. The contract is on a B2B basis within the banking and investment banking industry.

🏢 Summary: Senior Fullstack .NET Developer role focused on modernizing a legacy business process management platform within a digital banking environment. The position involves rebuilding applications from .NET Framework to modern .NET, developing React frontend components, and deploying scalable solutions to Kubernetes. You will contribute to system design, automated testing, and AI-assisted development in an enterprise Agile setup. 🗂️ Requirements: 5+ years of experience with C# and .NET, Experience modernizing legacy applications from .NET Framework, Strong knowledge of React, Practical experience with LLM tools (Claude, Codex), Experience with automated testing, Hands-on experience with Docker and Kubernetes, Experience designing and implementing enterprise applications, Strong knowledge of MS SQL, Experience with Git, JIRA, and TeamCity 📃 Skills: CSharp, DotNet, DotNetFramework, React, Kubernetes, Docker, MSSQL, Git, JIRA, TeamCity, Claude, Codex, Agile 🏢 Description: Unleash innovative web solutions — shape the future of digital banking experiences! Łódź-based opportunity with hybrid work model (2 days in the office/month). As a Senior Fullstack .NET React Developer , you will be working for our client, a leading financial institution focused on delivering innovative digital banking solutions. You will join a strategic modernization initiative involving the redevelopment of a business process management platform. The project focuses on rebuilding legacy applications from .NET Framework to modern .NET technologies, migrating infrastructure from on-premises environments to Kubernetes, and implementing high-quality engineering practices. You will collaborate closely with AI-powered development tools, contribute to system design decisions, and help deliver scalable, secure, and maintainable solutions in a complex enterprise environment. Your main responsibilities: Develop and maintain backend services using .NET and C# Rebuild legacy applications from .NET Framework to modern .NET architecture Design and implement frontend components using React Create and maintain automated unit and regression tests Collaborate with business stakeholders to analyze and refine requirements Design scalable and maintainable software solutions Integrate applications with databases and external services Utilize LLM-based tools such as Claude and Codex to support software development activities Participate in code reviews and ensure adherence to development standards Deploy and support applications running in Kubernetes environments Work closely with cross-functional teams in an Agile delivery model You're ideal for this role if you have: At least 5 years of experience in software development using C# and .NET Experience with .NET Framework and modernizing legacy code Good knowledge of React Practical experience working with LLM tools such as Claude and Codex Strong experience with automated testing Hands on experience with Docker and Kubernetes Experience designing and implementing enterprise applications Strong knowledge of MS SQL Experience using Git, JIRA, and TeamCity Ability to work independently while collaborating effectively within a team English skills sufficient to write and understand technical documentation Nice to have: Knowledge of message brokers, especially RabbitMQ,

🏢 Summary: Senior Full Stack Developer role focused on building enterprise-grade applications for capital markets and risk using React and C# .NET Core. The position involves developing scalable microservices, REST APIs, modern web UIs, and data-driven solutions in a cloud environment. Responsibilities include CI/CD implementation, event-driven architecture, cloud migration, and Power BI reporting. 🗂️ Requirements: Strong experience with React and TypeScript, Strong experience with C# and .NET Core, Experience building REST APIs, Experience developing microservices and distributed systems, Experience with CI/CD pipelines, Experience with Azure or AWS cloud platforms, Experience with Power BI and data modeling, Strong SQL and database knowledge, Experience with Docker and Kubernetes, Experience in capital markets domain especially credit risk or market risk, Strong understanding of software architecture and system design 📃 Skills: React, TypeScript, JavaScript, C#, DotNetCore, REST, Microservices, Azure, AWS, PowerBI, SQL, Docker, Kubernetes, Kafka, AzureDevOps, Jenkins, GitHubActions 🏢 Description: About the Role We are looking for a Senior Full Stack Developer with strong expertise in React on the frontend and C# .NET Core on the backend to build and enhance enterprise-grade applications in the capital markets and risk domain. The role involves developing scalable microservices, modern web applications, and data-driven solutions in a cloud environment. Key Responsibilities Design, develop, and maintain full stack applications using React and C# .NET Core Build and maintain REST APIs and microservices in distributed environments Develop modern, responsive UI components using React, TypeScript, and modern frontend patterns Work closely with business stakeholders in capital markets and risk domains (credit risk, market risk) Develop and maintain Power BI dashboards and data models for business reporting Implement and maintain CI/CD pipelines and automated deployment processes Contribute to event-driven architecture using tools such as Kafka or similar messaging technologies Participate in cloud migration and modernization initiatives (Azure or AWS) Ensure code quality through testing, code reviews, and best engineering practices Mentor junior developers and contribute to architectural decisions Requirements Strong experience with React, JavaScript/TypeScript Strong experience with C#, .NET Core, REST APIs Experience building microservices and distributed systems Experience with CI/CD tools (Azure DevOps, Jenkins, GitHub Actions) Experience with Azure or AWS Experience with Power BI and data modeling Strong SQL and database knowledge Experience with Docker / Kubernetes Experience working in capital markets , especially credit risk or market risk Strong understanding of software architecture and system design Excellent communication skills and experience working with business stakeholders