Senior Full-Stack Software Engineer (.NET, React)

We’re looking for a Full-Stack Software Engineer to work on the project of our Client. The project is an online payment platform for local government. Residents of cities, towns, and utilities use it to pay utility bills, taxes, citations, permits, and fees. Municipal staff use it to manage billing, autopay, imports, and reporting. Every day the platform handles payments that residents depend on and that public agencies have to reconcile exactly. The current system grew over many years on PHP and Angular (AngularJS through current Angular), on top of MySQL and .NET Framework services. The Client is replacing it with a modern stack: a Next.js/React/TypeScript front end, .NET 8+ services, and cloud-native deployment on Azure. You’ll be working on both sides of the rewrite: building the new platform and understanding the old one well enough to move its behavior over safely. Responsibilities: - Build and maintain customer-facing features using Next.js, React, and TypeScript for the new resident portal - Develop and maintain back-end services in C#, including ASP.NET Web API and MVC on .NET Framework 4.8, as well as modern services on .NET 8/10 - Contribute to the legacy system modernization and migration - Own features end-to-end, from requirements clarification and technical design through implementation, deployment, and ongoing support - Design, develop, and optimize data solutions in MySQL, MS SQL Server, and Azure SQL, including schema design, stored procedures, migrations, query optimization, and performance tuning - Develop and maintain background processing using Hangfire for scheduled tasks, payment processing, bill imports, notifications, and reconciliation - Participate in architecture and system design decisions, ensuring scalability, modularity, maintainability, reliability, security, and cost efficiency - Build, deploy, and maintain applications in Azure, leveraging Container Apps, App Service, Container Registry, Key Vault, and Application Insights - Work with Terraform, Docker, GitHub Actions, and Azure DevOps pipelines - Ensure application security through secure coding practices, proper authentication and token handling, secrets management, CSP, CORS, OWASP principles, and careful handling of payment and personal data - Troubleshoot complex technical issues, identify performance bottlenecks, and improve application reliability, monitoring, and observability - Maintain high engineering standards through code reviews, automated unit and integration testing, technical documentation, and continuous improvement of development processes - Leverage AI coding assistants and AI-assisted development workflows to improve delivery efficiency, code quality, and engineering productivity - Proactively identify and manage technical debt, proposing practical improvements while balancing business priorities and delivery timelines - Collaborate with Software Engineers, QA Engineers, and stakeholders, sharing technical knowledge, providing constructive feedback, and communicating technical decisions and trade-offs clearly Requirements: - Strong C# and .NET expertise: .NET Framework 4.8 (ASP.NET Web API / MVC) and .NET 8 or later, plus Entity Framework / EF Core - Solid SQL database knowledge, including MySQL and MS SQL Server, writing stored procedures, designing schema changes, and reading query plans - Working knowledge of Node.js tooling (npm/pnpm, build pipelines) - Day-to-day fluency with Git/GitHub and experience working in Jira-based Agile teams - A good grasp of web security basics: authentication tokens, CORS, CSP, XSS/CSRF, and keeping secrets out of code - Ability to work productively in large, older codebases: reading before changing, making safe incremental improvements, and leaving code better than you found it - English level — Upper-Intermediate or higher Will be a plus: - Strong knowledge of TypeScript/JavaScript, with Production experience in Angular and/or React plus Next.js (App Router) - PHP experience, especially in maintaining or migrating legacy PHP/MySQL applications - Expertise with Azure, including Container Apps, App Service, Key Vault, Application Insights, Entra ID, and Azure DevOps - Ability to leverage Terraform and Docker - Knowledge of Hangfire or similar job-scheduling frameworks - Skills with Playwright or similar end-to-end testing solutions - Experience with Express.js - Expertise in Tailwind CSS, design systems, and accessibility (WCAG) - Experience with white-label/multi-tenant applications or iframe embedding and postMessage messaging - Payments, billing, or public-sector/GovTech experience (PCI awareness, ACH and card processing, reconciliation) - Comfort in using AI coding assistants as part of a disciplined engineering workflow We offer: - Modern technology: projects built on current stacks and tools, with room to explore new technologies and bring better engineering approaches to your team - Ownership culture: a team of professionals who look beyond the task, understand the client’s business and propose solutions that make the product better. People here own outcomes, flag risks early, and hold a high engineering standard - Professional growth: lead or join Competence Clubs, speak at TechTalks, get company-paid certifications, grow with our professional library and learning platforms, and improve your English, German, or Polish via courses or speaking clubs - Flexible work: remote-first, equipment and IT support, plus availability to work from offices in Lviv and Rzeszów - Time off & well-being: 18 paid vacation days, 12 paid sick days, medical insurance or a monthly health & sports budget*, psychologist consultations, paid leave for life events, and paid maternity leave (*The format varies depending on your cooperation model) Відгукнутись на вакансію