Senior C# Engineer

🏢 Summary: B2B opportunity for an experienced .NET Back-End Developer to build modern, scalable cloud-based solutions using C# and Azure. The role focuses on designing high-performance services, working with CosmosDB, and collaborating in an Agile team with exposure to AI-assisted development tools. This is a fully remote position with competitive hourly rates and long-term cooperation. 🗂️ Requirements: 5+ years of professional experience in .NET development, Strong experience with C#, Proven experience with Azure services, Experience with CosmosDB, Experience with TypeScript or JavaScript, Bachelor’s degree in Computer Science or related field, Ability to align with US-based team working hours, English language proficiency 📃 Skills: .NET, C#, Azure, CosmosDB, TypeScript, JavaScript, AI, Playwright, Selenium, Drupal 🏢 Description: For our client from the technology and industrial solutions sector, we are looking for a .NET Back-End Developer to join a talented development team working on modern, scalable software solutions. Responsibilities: Design, develop, and maintain high-performance back-end services using .NET and C#. Work extensively with Azure cloud services and CosmosDB to build scalable and resilient solutions. Collaborate with front-end developers, product owners, and other team members to integrate back-end services. Participate in code reviews, architectural discussions, sprint planning, and other Agile ceremonies. Use modern development tools and practices to improve productivity, code quality, and maintainability. Explore and apply AI-assisted tools where appropriate to support development, documentation, troubleshooting, and workflow efficiency. Contribute to improving development processes, engineering practices, and team knowledge sharing. Be a proactive problem-solver and continuous learner, staying current with relevant technologies and industry trends. Requirements: Application Development Experience: 5+ years of professional experience in .NET development. Cloud Development Expertise: Proven experience with C#, Azure services, and CosmosDB. Scripting / Front-End Knowledge: Experience with TypeScript preferred, or JavaScript. AI Tool Familiarity: Interest in or hands-on experience using AI tools to support software development, productivity, documentation, research, or troubleshooting. Educational Background: Bachelor’s degree in Computer Science or a related field. Flexibility: Ability to align somewhat with US-based team working hours. Communication: English language proficiency. Stack: Cloud: Azure, CosmosDB Back-End: .NET, C# Scripting / Tooling: TypeScript preferred, JavaScript acceptable Productivity / AI Tools: Familiarity with AI-assisted development or productivity tools is a plus Nice to have: Domain Knowledge: Background in Electrical Engineering or a related technical field. Background or interest in analog and mixed-signal hardware design. Knowledge of hardware or system simulation concepts. CMS Knowledge: Familiarity with Drupal. Test Automation Exposure: Familiarity with tools like Playwright or Selenium. Quality Mindset: Prior QA experience or understanding of QA methodologies is welcome. Offer: Cooperation based on a B2B contract and rate: 140-170 PLN/hour 100% remote work The support of a dedicated mentor. In the relationship, we focus on direct communication. When you join speedapp, you will be put in touch with a dedicated mentor who will make sure that you enjoy working with us and with the client. Events and integration meetings, as well as participation in various initiatives, e.g., sports. Access to the benefits offering (medical care, Multisport card). About Speedapp At speedapp, we believe that an organization is only as good as the people who make it up. We are a team of IT experts and other professionals working for our clients around the world (including Israel, Austria, USA). We go far beyond the HR category. We build IT teams and also help manage them. 👉 10 years of experience 👉 +100 clients worldwide +300 hires per year 💎 We have won the prestigious "Forbes Diamonds" award four times (2022, 2023, 2024, 2025). We are a member of the European Fast Growth Icons network and FinTech Poland. We are ranked 18th among the 100 fastest growing companies 2023 by Clutch.

🏢 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 a custom industrial application supporting end-to-end production and logistics processes. The position involves backend development in .NET, frontend development with Angular, and designing microservices-based solutions deployed in AWS. The project emphasizes scalability, traceability, and continuous product improvement. 🗂️ Requirements: Minimum 5 years of commercial experience as a .NET Developer, Strong hands-on experience with .NET in backend development, Practical experience with Angular in frontend development, Experience with microservices-based architecture, Experience with AWS cloud services 📃 Skills: .NET, Angular, AWS, Microservices 🏢 Description: We are looking for a Senior .NET Developer to join a long‑term product development project in the industrial and manufacturing domain. The role focuses on building and maintaining a custom‑built application that supports end‑to‑end production and logistics processes for industrial clients. The project uses modern technologies and follows an innovation‑driven approach, with strong emphasis on process traceability, scalability, and continuous improvement. Your tasks Develop and maintain backend solutions using .NET for a custom industrial application Implement new product functionalities according to business and process requirements Build and extend frontend features using Angular Design and develop solutions based on a microservices architecture Develop, deploy, and maintain solutions in an AWS cloud environment Requirements Minimum 5 years of commercial experience as a .NET Developer Strong hands‑on experience with .NET in backend development Practical experience with Angular in frontend development Experience working with microservices‑based architectures Experience working with AWS cloud services Fluency in English Residing in Poland required

🏢 Summary: Remote Senior .NET Developer role focused on extending and scaling banking systems, integrating securities and banking operations, and supporting product control and risk management applications. The position requires full-stack .NET and Angular development, testing expertise, and experience with cloud-oriented system scaling. 🗂️ Requirements: 5+ years of .NET development experience, Angular proficiency, Full-stack development experience, Hands-on code testing experience, SOLID design principles, Document-based database experience, MongoDB familiarity, Unit and integration testing experience, Event-based messaging framework experience, Banking industry experience 📃 Skills: .NET, Angular, SOLID, MongoDB, Testing, Messaging, Banking 🏢 Description: Introduction & Summary We are seeking a highly skilled Senior .NET Developer with a strong background in developing and extending systems for the banking industry. The ideal candidate will possess at least 7 years of experience in .NET development along with proficiency in front-end technologies, particularly Angular. This is a 100% remote position requiring a proactive approach towards scaling applications and supporting cloud-based solutions. Main Responsibilities - Develop and extend systems to support additional entities. - Merge securities and banking operations seamlessly. - Provide support for 17 applications including product control and risk management. - Utilize in-house development frameworks. - Scale systems for cloud-based operations to onboard new entities. Key Requirements - 5+ years of experience in .NET development. - Proficiency in front-end technologies, specifically Angular. - Full-stack development experience with hands-on code testing. - Solid understanding of SOLID design principles. - Experience with document-based databases. - Familiarity with MongoDB. - Integrated experience with unit and integration testing. - Experience with event-based messaging frameworks. - Background in the banking industry. Nice to Have - Advanced cloud computing skills. - Experience with containerized solutions.

🏢 Summary: Software Engineer role focused on building scalable, high-quality applications with primary emphasis on frontend development in Angular and Flutter, while supporting backend services in C#/.NET and SQL. The position involves developing RESTful APIs, integrating frontend and backend components, and ensuring security, performance, and scalability in an Agile environment. 🗂️ Requirements: 2+ years commercial software development experience, Strong knowledge of Angular and Flutter, Strong knowledge of HTML, CSS, TypeScript, JavaScript, Experience with C# and .NET, Experience with SQL Server, Experience designing and integrating REST APIs, Familiarity with Git, Experience working in Agile environment 📃 Skills: Angular, Flutter, HTML, CSS, TypeScript, JavaScript, C#, .NET, SQL, SQLServer, NoSQL, Git, Agile, REST, APIs 🏢 Description: Our Client is a fast-growing technology group headquartered in London, focused on building industry-specific payment solutions for small and medium-sized businesses. Client develops tailored software solutions across multiple sectors, including retail, services, healthcare, sports, public sector, and non-profit . The company operates across several locations in the UK and has a technology hub in Kraków , offering an international, product-driven working environment. Your role We are looking for a Software Engineer to join a dynamic development team and contribute to building high-quality, scalable applications with real business impact. The role focuses primarily on frontend development using Angular and Flutter , while also supporting backend services built with C#/.NET and SQL . You will work closely with cross-functional teams to deliver secure, performant, and user-friendly solutions, with opportunities to grow across multiple technologies. Your responsibilities Develop, maintain, and enhance applications using Angular and Flutter Support backend development with C#/.NET and SQL Design and implement RESTful APIs and integrate them with frontend applications Ensure application security, performance, and scalability Perform unit testing, debugging, and participate in code reviews Work in Agile sprints (planning, development, testing, deployment) Collaborate closely with Product teams to translate business requirements into technical solutions Stay up to date with emerging technologies and propose improvements Our requirements 2+ years of commercial software development experience Strong knowledge of Angular, Flutter, HTML, CSS, TypeScript, and JavaScript Experience with C#/.NET and SQL Server (NoSQL is a plus) Familiarity with Git and Agile methodologies Strong problem-solving skills and attention to detail Very good communication in English and teamwork skills Proactive attitude and willingness to learn Nice to have Interest in cross-platform development What we offer Long-term project Chill zone with a football table Integration events Collaborative, product-focused team Opportunity to grow within a fast-evolving tech company Participation in meaningful products used daily by real customers 📌 Please note: we will contact selected candidates only . TQLO Sp. z o.o. Registered employment agency (KRAZ): 33580

🏢 Summary: The offer is for a Senior .NET Developer responsible for improving and refactoring core backend systems to enhance structure, maintainability, and security. The role focuses on reducing technical debt, enabling automation and AI integration, and ensuring high code quality through testing and CI/CD practices. The position involves hands-on development within legacy or monolithic environments and driving system modernization. 🗂️ Requirements: 5+ years experience in .NET / C# backend development, Experience with legacy or monolithic systems, Strong knowledge of clean code principles, Proven experience in refactoring existing codebases, Strong SQL and backend integration experience, Experience with APIs and service-based architecture, Experience with CI/CD pipelines, Experience with automated testing, Familiarity with TDD or BDD practices, Experience with Gherkin, SpecFlow, Cucumber or similar, Experience using AI tools in development workflows, Understanding of code structuring for automation and AI integration 📃 Skills: .NET, C#, SQL, APIs, CI/CD, TDD, BDD, Gherkin, SpecFlow, Cucumber, AI, Git, Docker, .NETCore 🏢 Description: Introduction & Summary: We are seeking a Senior .NET Developer with 5-8+ years of experience in backend development and .NET engineering. The successful candidate will drive improvement in code quality, reduce technical debt, and support system structuring for better predictability. With a focus on future automation and AI capabilities, you will help ensure code understandability, maintainability, and security. Main Responsibilities: Responsible for hands-on development and refactoring of core systems, with the aim of enhancing their structure and predictability. Develop and improve .NET-based systems. Reduce technical debt and increase maintainability. Support safe and efficient delivery. Ensure code is understandable, maintainable, and secure. Make systems testable and observable. Facilitate automation of workflows. Key Requirements: Strong experience with .NET / C#. Experience working with legacy or monolithic systems. Strong understanding of clean code principles. Experience with refactoring and improving existing codebases. Strong SQL and backend integration experience. Experience with APIs and service-based architecture. Experience with CI/CD pipelines. Experience with automated testing. Familiarity with TDD / BDD and security by design thinking. Experience with Gherkin / SpecFlow / Cucumber or similar. AI-related: Experience using AI tools in development workflows. Understanding of code structuring for automation and AI integration. Experience using AI for debugging, testing, or documentation support. Nice to Have: Experience with .NET Core. Experience with containerization. Exposure to AI-assisted testing or development tools. Experience improving system observability.

🏢 Summary: Backend Developer (.NET) role focused on development, maintenance, and modernization of an existing logistics system. The position involves working with legacy code, fixing bugs, refactoring, and improving business logic within a live operational environment. The role requires close collaboration with development and analytics teams. 🗂️ Requirements: 3–5 years of experience with .NET, Proficiency in C#, Experience with ASP.NET MVC or ASP.NET Core, Strong knowledge of SQL Server, Experience working with legacy codebases, Ability to debug and analyze complex issues, Experience with REST API, English level B2 minimum 📃 Skills: .NET, C#, ASP.NET, MVC, Core, SQL, SQLServer, REST, EntityFramework, Docker, UnitTesting 🏢 Description: Organizacja z branży logistycznej, rozwijająca własne systemy operacyjne, poszukuje osoby na stanowisko Backend Developer (.NET). Rola skupiona jest na rozwoju i stabilizacji istniejącego systemu oraz stopniowym jego unowocześnianiu. Zakres obowiązków Rozwój i utrzymanie systemu w technologii .NET Analiza i rozwiązywanie błędów w systemie (bugfixy) Refaktoryzacja istniejącego kodu Analiza logiki biznesowej i jej usprawnianie Współpraca z zespołem developerskim i analitycznym Praca z kodem bez pełnej dokumentacji Wymagania Min. 3–5 lat doświadczenia w .NET Dobra znajomość: C# ASP.NET (MVC / Core) SQL Server Doświadczenie w pracy z istniejącym kodem (legacy) Umiejętność debugowania i analizy problemów Znajomość REST API Znajomość języka angielskiego na poziomie minimum B2 Mile widziane Entity Framework (klasyczny i Core) Podstawy testów jednostkowych Znajomość Docker Oferujemy Pracę przy systemach o realnym wpływie na operacje biznesowe Możliwość rozwoju technologicznego Stabilne zatrudnienie Wpływ na jakość i rozwój systemu

🏢 Summary: Senior Backend Engineer role focused on building and scaling a cloud-based SaaS platform using modern .NET services and REST APIs. The position involves designing distributed systems, improving reliability and observability, and working with cloud and container environments. You will contribute to technical decisions and engineering best practices within a collaborative team. 🗂️ Requirements: 5+ years backend development experience, Experience with SaaS and web applications, Strong knowledge of C#, Strong knowledge of modern .NET/.NET Core, Solid computer science fundamentals, Experience with distributed systems design, Experience with cloud platforms, Experience with containers and orchestration, Understanding of concurrency and performance, Knowledge of authentication and authorization mechanisms 📃 Skills: C#, .NET, .NETCore, REST, Azure, AWS, GCP, Kubernetes, Kafka, RabbitMQ, SQS, Docker, SQL, HTML, CSS, JavaScript 🏢 Description: We’re hiring a Senior Backend Engineer to help build and scale a cloud-based SaaS platform. You’ll work on modern .NET services and APIs, improve reliability and observability, and contribute to technical decisions as part of a collaborative engineering team. Responsibilities: Build and maintain backend services and REST APIs in C# / .NET (.NET Core). Design scalable solutions for distributed systems (async workflows, messaging, integrations). Work with cloud services (Azure/AWS/GCP) and container environments (e.g. Kubernetes). Strengthen system reliability with logging, metrics, tracing, and monitoring. Support secure access patterns: authentication/authorization, API gateway concepts. Contribute through code reviews, good engineering practices, and automation. Requirements: 5+ years of backend development experience, including SaaS and web applications. Strong knowledge of C# and modern .NET + solid CS fundamentals. Familiarity with containers/orchestration and cloud-native approaches. Experience with some of: Kafka/RabbitMQ/SQS, workflow orchestration, job scheduling, search. Good understanding of concurrency and performance. Strong communication skills; Agile/Scrum is a plus. Bonus: basic front-end knowledge (HTML/CSS/JS).

🏢 Summary: Full-stack SharePoint Developer role focused on developing, supporting, and optimizing IT systems for Frontex. The position involves backend, frontend, and cloud development, technical documentation, software lifecycle ownership, and support activities in an enterprise environment. Candidates should have strong SharePoint, .NET, React, and Azure DevOps experience and be comfortable contributing to architecture, QA, deployment, and team leadership tasks. 🗂️ Requirements: Bachelor’s degree in ICT or related field, Minimum 2 years of experience in Full-stack SharePoint support or development, Experience with custom SharePoint solutions, SDK, workflows, timer jobs, and features, Knowledge of Microsoft .NET/.NET Core, Experience with MS SQL Server and T-SQL, Experience with Azure DevOps pipelines, Knowledge of HTML and CSS responsive design, Experience with JavaScript, TypeScript, and React, Knowledge of REST, HTTP APIs, and Web Services, Understanding of UML application design, Experience working with Scrum methodologies, Experience with full-tier development, Advanced enterprise software development skills, Experience delivering at least one solution through the full software lifecycle, Strong problem-solving and technical documentation skills, Intermediate-level software development certification, English proficiency at B2 level or higher, Availability to work from the client’s office at least 5 times per month 📃 Skills: SharePoint, .NET, SQL, T-SQL, Azure, DevOps, HTML, CSS, JavaScript, TypeScript, React, REST, HTTP, UML, Scrum 🏢 Description: About the project Join an innovative environment and turn ambitious ideas into reality together with Britenet. We are a European IT company with strong Polish roots, already trusted by more than 200 business partners from all over the world. We're looking for an experienced developer who combines both SharePoint and frontend skills. This time you have the chance to be part of a project related to the development, consulting and support of IT systems for Frontex. The European Border and Coast Guard Agency supports EU Member States and Schengen-associated countries in the management of the EU's external borders and the fight against cross-border crime. Our expectations -Bachelor’s degree in ICT or a related field. -Minimum 2 years in a Full-stack SharePoint support or developer role (custom solutions, SDK, workflows, timer jobs, features, etc.). -Knowledge and experience with: Backend & Cloud: Microsoft .NET/.NET Core, MS SQL Server (T-SQL), and Azure DevOps pipelines. Frontend: HTML/CSS (responsive design), JavaScript/TypeScript (ES6+ features like arrow functions and destructuring), and React. APIs: Web Services, REST, and HTTP APIs. Architecture & Design: UML application design, Scrum methodologies, and full-tier development (data, business logic, and UI layers). -Advanced in developing enterprise-level software systems. -Proven experience taking at least one solution through its complete lifecycle. -Strong problem-solving, effective technical documentation, and an openness to technical team leadership tasks. -Certification: At least one intermediate-level software development certification relevant to the domain (or international equivalent). -Proficiency in English at a minimum B2 level (certification is an advantage). -Readiness to work from the client's office occasionally – at least 5 times per month Key tasks -Design and develop the system -Translate requirements into design -Optimize software from performance, security and quality points of view -Produce technical documentation -Estimate effort and time for development -Set software development standards -Propose technical solutions for business needs and technical problems -Collect and interpret software metrics -Contribute to: requirements analysis, testing, quality assurance, change management, deployment, leading teams, configuration, releases management -Act as 2nd and 3rd line support

🏢 Summary: The offer is for a .NET Developer responsible for building and enhancing scalable backend systems and REST APIs for global travel platforms. The role involves contributing to architecture, optimizing performance, and collaborating in an agile environment to deliver reliable, high-quality software. It includes hybrid work, international projects, and professional development opportunities. 🗂️ Requirements: Minimum 3 years of commercial experience with .NET development, Strong knowledge of ASP.NET MVC, Experience developing REST APIs, Experience working in agile software development teams, Good knowledge of MS SQL, Good knowledge of Elasticsearch, Experience with CI/CD tools (Git, TeamCity or similar), Experience writing unit and integration tests, Ability to write clean, maintainable, and well-tested code, Very good English communication skills 📃 Skills: .NET, ASP.NET, MVC, REST, MS SQL, Elasticsearch, Git, TeamCity, CI/CD, UnitTesting, IntegrationTesting, Umbraco, Angular, AWS 🏢 Description: We are looking for a .NET Developer to join our team and help build scalable, high-quality solutions that power our global travel platforms. In this role, you will work on the development and enhancement of backend systems, contribute to architectural decisions, and collaborate with cross-functional teams to deliver reliable and efficient software used by customers worldwide. Your responsibilities Design, develop, and maintain applications using .NET technologies Translate business requirements into scalable and maintainable technical solutions Develop and enhance REST APIs and backend services Maintain, troubleshoot, and improve existing applications Refactor and optimize code to improve performance, scalability, and maintainability Write clean, well-structured, and testable code following best practices Participate in code reviews and contribute to improving development standards Identify and resolve performance bottlenecks and system issues Contribute to application architecture, technical design, and system documentation Collaborate closely with developers, QA engineers, Product Owners, and other stakeholders in an agile environment Our requirements At least 3 years of commercial experience with .NET development Strong knowledge of ASP.NET MVC and REST APIs Experience working within agile software development teams Good knowledge of MS SQL and Elasticsearch Experience with CI/CD tools and practices (Git, TeamCity or similar) Experience writing unit and integration tests Ability to write clean, maintainable, and well-tested code Very good English communication skills Nice to have Experience with Umbraco CMS Experience with Angular Knowledge of AWS services and cloud-based solutions How we work Clean Code principles Design patterns and software engineering best practices Code reviews and knowledge sharing Static code analysis Continuous Integration and Continuous Deployment (CI/CD) Agile and collaborative development environment What we offer Hybrid work model (1–2 days per week in our Katowice office) Opportunity to work on international, large-scale projects Attractive remuneration paid in EUR Flexible working hours Individual development budget Partially or fully funded training and certifications English lessons Mentoring and support from experienced technical leaders Participation in conferences in Poland and abroad A culture focused on learning, collaboration, and knowledge sharing Space to innovate and bring your own ideas to life Support for IT community initiatives