Senior .Net Developer (Mobile)

🏢 Summary: Senior Mobile Developer role leading the design and delivery of a secure, mobile-first platform integrated with backend, access control, payments, and operational systems. The position combines hands-on mobile development with architectural influence over a .NET/C# backend and technical leadership responsibilities. Offers ownership of product direction, team building, and long-term platform strategy with relocation and visa support available. 🗂️ Requirements: Strong commercial experience developing and shipping mobile applications, Experience with mobile security and biometrics, Experience implementing push notifications and BLE, Experience with API-driven architectures, Basic understanding of .NET/C# backend, Experience integrating third-party systems and operational platforms, Knowledge of CRM, CMS, ERP, payment and reporting systems, Understanding of cloud infrastructure, Strong documentation and security mindset, English or Polish language proficiency 📃 Skills: Mobile, iOS, Android, Biometrics, BLE, APIs, .NET, C#, CRM, CMS, ERP, Payments, Cloud 🏢 Description: Mobile Developer (.NET) — B2B Contract | Warsaw | Start Immediately $6,000–6,500/month · Full-time · In-office · Relocation bonus · Milestone bonuses The Opportunity We're building a mobile app that talks to real-world access control and operational systems—secure logins, biometrics, BLE-based access, payments, and reporting, all in one platform. We need a hands-on mobile developer to own the app and ship features fast, working side-by-side with our .NET backend team and directly with the CEO. This starts as a B2B contract with real potential to grow into a bigger, long-term role—architecture, team leadership, the works—if it's a fit on both sides. This is a senior-level role only. We need someone with a proven track record—live, shipped apps in production and a portfolio to show it. No juniors, no mid-level, no exceptions. What You'll Build Mobile app features (iOS/Android or cross-platform) — real, production, shipping code. Authentication, biometrics, push notifications, and BLE functionality. API integrations with our .NET/C# backend. Direct input into how the app connects to our customer portal, payments, and reporting systems. Fast decisions, zero bureaucracy—you work directly with the CEO and core team. What You Bring Proven track record: Live apps you've shipped that are currently in production, with a portfolio or App Store/Google Play links to prove it. Strong senior-level commercial experience—this is not an entry-level role. Comfortable working with APIs and collaborating with a backend team (bonus if you know .NET/C#). Working knowledge of mobile security fundamentals: authentication, permissions, push notifications, and BLE. Independent, clear communicator who delivers. Based in Warsaw or willing to relocate, and available to start immediately. Nice to Have .NET/C# experience. CRM/CMS experience (e.g. Umbraco). Access control or IoT/BLE hardware integration experience. Interest in leading a mobile team as the product grows. What's In It for You $6,000–6,500/month (B2B contract). Relocation bonus if you're moving to Warsaw. Milestone bonuses for major deliveries (first release, key integrations, platform go-live). Modern Warsaw office. Direct access to the CEO—your work shapes the product. Fast-moving, low-bureaucracy environment with genuine long-term growth opportunities. Please include links to live apps or a portfolio with your application. Applications without proof of shipped work will not be considered. Start immediately. Interview process takes days, not weeks.

🏢 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: Hands-on Technical Lead (.NET) role focused on designing and delivering scalable, high-performance software solutions for logistics platforms. The position combines architectural decision-making, microservices and cloud-based system design with active coding and team leadership. You will drive technical direction, ensure best engineering practices, and oversee Azure-based cloud environments and CI/CD processes. 🗂️ Requirements: 8+ years of software engineering experience, Minimum 2 years in technical leadership role, Strong experience with .NET and C#, Experience designing and developing scalable RESTful APIs, Knowledge of microservices architecture and design patterns, Experience with message queues, Experience with relational or NoSQL databases, Experience with Azure and GCP cloud services, Experience with Docker and Kubernetes, Experience with CI/CD practices, Experience with Agile methodologies, Experience managing software releases and performance monitoring, Advanced English proficiency (B2+) 📃 Skills: .NET, C#, Node.js, REST, Microservices, RabbitMQ, Kafka, MySQL, MongoDB, CosmosDB, Azure, GCP, Docker, Kubernetes, CI/CD, Agile 🏢 Description: As Technical Lead (.NET) you join a team of talented engineers and developers working together to transform final mile logistics and supply chain operations.  Your role will be a hands-on leadership position where you guide engineering teams to deliver scalable, high-quality software solutions. This is the perfect role for experienced engineers who thrive in technical decision-making, architecture, and mentorship—while staying engaged in hands-on coding. Key Responsibilities: Define the technical direction, making pivotal design decisions to ensure our architecture is scalable, maintainable, and high performing. Stay hands-on with coding, leading by example and ensuring adherence to best practices in security, performance, development, deployment and observability. Implement scalable microservices, API gateways, and event-driven architectures, ensuring high availability, disaster recovery and fault tolerance strategies are in place. Champion high-quality code testing, automation testing, and continuous integration/continuous deployment (CI/CD). Oversee Azure-based cloud architecture, optimizing performance, security, and cost efficiency. Directly supervise, mentor, and develop a team of 5-7 engineers, providing career guidance and fostering a culture of engineering excellence full of collaboration, accountability and professional growth. Actively recruit and interview top talent to strengthen the engineering team. Collaborate with Product Managers to align roadmap priorities, streamline development workflows, and enhance team processes for improved efficiency and operational excellence. Optimize development workflows and SDLC processes to improve team velocity, efficiency and maintain low cycle times. Establish engineering KPIs and leverage data-driven insights to enhance performance. Stay updated with industry trends and emerging technologies to continuously improve our platform. Requirements: 8+ years in software engineering (ideally .NET C#), with at least 2 years in a technical leadership role. Experience in other tech stacks like Node.js as a plus. Demonstrated expertise in designing and developing scalable APIs, with knowledge of RESTful principles and best practices. Knowledge of microservices architecture and related design patterns / best practices. Experience with message queues (e.g., RabbitMQ, Kafka) and event-driven architecture / patterns. Experience with databases such as MySQL, MongoDB, CosmosDB or similar. Experience utilizing cloud services (Azure and GCP) and containerization (Docker, Kubernetes). Experience with Agile methodologies and CI/CD practices. Experience in managing software releases, performance monitoring, and reliability improvements. Strong problem-solving skills and ability to work in a fast-paced environment. Ability to explain complex technical concepts to engineers, executives, and cross-functional teams. Advanced proficiency in English, both written and spoken (B2+). Office location: Kraków, Poland Work Style: hybrid (2-3 days from the office / week preferred) Salary levels: 28 000 – 32 000 PLN/ month Take the next step in your career and become a part of OneRail’s exciting journey!

🏢 Summary: Full-stack role focused on leading frontend and mobile development with Angular and Flutter while supporting backend services in C#/.NET and SQL Server. The position involves building scalable applications, integrating REST APIs, and contributing across the full Agile lifecycle through CI/CD deployment. Hybrid work in Kraków with B2B contract. 🗂️ Requirements: 3+ years professional experience, Strong proficiency in Angular, Strong proficiency in Flutter, Strong proficiency in TypeScript, Strong proficiency in HTML, Strong proficiency in CSS, Experience with C#, Experience with .NET, Experience with SQL Server, Experience designing and integrating REST APIs, Experience with Git, Experience working in Agile methodology, Ability to perform unit testing and debugging, Knowledge of performance, scalability and secure coding practices 📃 Skills: Angular, Flutter, TypeScript, HTML, CSS, C#, .NET, SQLServer, REST, Git, Agile, CI/CD, Testing, Debugging 🏢 Description: Join a dynamic development team in Kraków to build high-quality, scalable applications. This role is unique in its breadth: you will lead frontend and mobile efforts using Angular and Flutter , while simultaneously supporting backend services powered by C#/.NET and SQL . You will be part of a product-focused team where your work directly impacts real customers daily, moving projects from initial requirements through Agile sprints to final deployment. Details Location: Kraków (Hybrid) Rate: 90-105 PLN/h net + VAT (B2B). Employment Type: Full-time. Seniority: 3+ years of professional experience. Start Date: ASAP. Responsibilities Cross-Platform Development: Building and maintaining applications using Angular (web) and Flutter (mobile). Backend Support: Developing and supporting services with C#/.NET and SQL Server . API Integration: Designing and implementing RESTful APIs and ensuring seamless frontend-to-backend connectivity. Quality Assurance: Performing unit testing, debugging, and participating in rigorous code reviews. Agile Collaboration: Contributing to the full lifecycle of Agile sprints, from planning to CI/CD deployment. Requirements Frontend/Mobile: Strong proficiency in Angular, Flutter, TypeScript , and modern CSS/HTML. Backend: Experience with C#/.NET and SQL Server (knowledge of NoSQL is a plus). Workflow: Familiarity with Git and Agile methodologies. Security: Awareness of performance, scalability, and secure coding practices. Nice to Have Mobile Extras: Experience with Ionic or Cordova . Cloud & DevOps: Familiarity with Azure/AWS , Azure Functions, and CI/CD pipelines. Identity: Knowledge of OAuth, JWT, or IdentityServer .

🏢 Summary: Senior .NET Developer role focused on building and maintaining secure, high-performance online banking solutions in a distributed Agile environment. The position involves developing backend features in .NET 8, optimizing SQL-based data access, and working with containerized applications. Hybrid work model with strong emphasis on reliability, security, and collaboration. 🗂️ Requirements: Minimum 4 years of experience in IT system development, Hands-on experience with .NET, especially .NET 8, Strong knowledge of PostgreSQL, Strong knowledge of MS SQL, Experience with Docker, Experience with Kubernetes, Practical experience in Agile software development, Experience in developing new features and maintaining existing systems, Good command of Polish, Legal right to work in the European Union 📃 Skills: .NET, C#, PostgreSQL, MSSQL, SQL, Docker, Kubernetes, Agile 🏢 Description: Ignite digital innovation — shape the future of online banking! Warszawa-based opportunity with hybrid work model (2 days in the office/month, up to 4 remote days/week). As a Senior .NET Developer , you will be working for our client, a leader in online banking, supporting the development and maintenance of secure, high-performance financial solutions. You’ll join a dynamic team dedicated to building cutting-edge banking functionalities, ensuring top-tier reliability and innovation. Operating within a distributed Agile environment, you’ll play a pivotal role in implementing complex backend logic while collaborating seamlessly across teams. This is your chance to contribute to transformative financial technology and accelerate your career growth. Your main responsibilities: Design and develop new features in .NET 8 to enhance banking solutions. Implement and optimize SQL-based data access for performance and security. Build and maintain containerized applications using Docker and Kubernetes. Collaborate with distributed teams within an Agile framework. Participate in the development of secure payment solutions. Share knowledge and mentor less experienced team members. Ensure code quality through reviews and testing. Maintain existing functionalities and address production issues. Manage your time effectively while working remotely. You're ideal for this role if you have: At least 4 years of experience in IT system development. Solid hands-on experience with .NET (especially .NET 8). 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 responsibilities. Experience developing new features and maintaining existing ones. Passion for software development and continuous learning. Experience with Docker and Kubernetes. It is a strong plus if you have: (optional) Certifications in relevant technologies. Experience with financial or payment systems. Language Required for the role: Good command of Polish. Eligibility to work on this 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: 100% remote B2B opportunity to lead a development team in building and maintaining scalable applications within an agile environment. The role combines hands-on full-stack development with strategic technical leadership, focusing on robust system architecture and faster delivery of new solutions. Long-term cooperation with a two-stage recruitment process including a technical test. 🗂️ Requirements: Proficiency in .NET, Proficiency in C#, Experience in full-stack development, Experience with front-end technologies, Experience with document-based databases, Knowledge of event-based messaging frameworks, Experience with cloud services, Experience with containerization, Ability to lead development teams, Experience working in agile environment 📃 Skills: .NET, C#, Angular, MongoDB, Cloud, Docker, Microservices, REST, Git 🏢 Description: Work model: 100% remote Start date: Flexible Rate: up to 215 PLN/h netto + VAT Contract : B2B, long-term cooperation (12-month contract up front + extensions) Recruitment process : 2 stages, including a technical test estimated to take 2-4 hours. Summary: The role focuses on leading the development team to create new solutions and maintain systems within an agile environment, emphasizing the importance of robust applications and strategic direction. Main Responsibilities: Lead the development team in creating and maintaining applications. Adopt wider technology practices and address the speed of new application delivery. Engage in hands-on development while guiding the strategic direction of projects. Collaborate with teams to gather specifications and perform technical analysis. Navigate complex systems and ensure they are built to scale. Manage developer quality and capacity amidst organizational constraints. Key Requirements: Proficient in .NET and C#. Experience with full-stack development, including front-end technologies. Familiarity with document-based databases. Knowledge of event-based messaging frameworks. Experience with cloud services and containerization. Nice to Have: Prior experience in the banking or financial services sector. Familiarity with Angular or other modern front-end frameworks. Experience with MongoDB or similar environments. Other Details: Environment: .NET, C#, Angular, MongoDB, moving towards cloud solutions. Team Structure: Full Stack Developers working closely with Business Analysts.

🏢 Summary: Senior .NET Developer role focused on building and architecting cloud-native backend systems with AWS and CI/CD automation. The position involves designing microservices-based solutions, writing high-quality testable code, and contributing across the full project lifecycle in a spec-driven environment. Fully remote B2B contract with long-term cooperation potential. 🗂️ Requirements: Experience with modern .NET / .NET Core, Experience with AWS or Azure, Knowledge of microservices architecture, Knowledge of distributed systems, Ability to design system architecture, Experience writing integration tests, Experience writing end-to-end tests, Familiarity with BDD approach, Experience with CI/CD automation 📃 Skills: .NET, NETCore, AWS, Azure, CI/CD, Microservices, DistributedSystems, C#, BDD, IntegrationTesting, E2ETesting, Architecture 🏢 Description: Join an international IT company specializing in cloud services, managed services, and digital transformation for enterprises. As a Senior .NET Developer with a focus on AWS and CI/CD automation, you will participate in the project by providing backend support to the Tech Lead and a team. Key responsibilities Designing and architecting system components, Writing high-quality, testable code in .NET, Contributing to the development of modern cloud-native solutions, Working across the full project lifecycle (from discovery to delivery), Participating in planning and analysis (discovery, planning), Working in a “spec-driven” approach (based on specifications), Co-creating and refining specifications, acceptance criteria, and architectural decisions. Ideal candidate profile Experience with . NET (Core / modern .NET), Azure or AWS , Knowledge of architecture: microservices, distributed systems, Ability to translate business requirements into technical architecture, Writing integration and end-to-end tests, Familiarity with BDD (Behavior-Driven Development) approach. Conditions Type of cooperation: B2B contract Initial contract duration: 1st June- End of February 2027, with the intention to extend the cooperation or move top performers to another project. Rate: 130 - 160 PLN/h Benefits: Private healthcare, Multisport card and life insurance Work model: 100% remote from any location in Poland Recruitment steps Phone call with a Recruiter - Oliwia (approx. 20 min.) Interview with Client : Introductory conversation with the delivery team: review of your experience vs project needs, light technical questions, and verification of your comfort in a fully English‑speaking, international environment. Introductory interview : discussion of experience in relation to project requirements, technical questions. Final technical interview with Client : in‑depth technical questions, possibly practical task to see how you think, ask questions, and structure solutions. Decision and feedback

🏢 Summary: Senior Full Stack Engineer role focused on building and optimizing React/TypeScript frontends and ASP.NET Core backend services supporting treasury workflows. The position involves designing scalable REST APIs, improving performance across the stack, and working with large datasets in production systems. Hybrid work model in Warsaw with strong emphasis on engineering best practices and reliability. 🗂️ Requirements: 5+ years of experience building production systems, Strong experience with C# and .NET ecosystem, Strong experience with ASP.NET Core, Strong experience with React, Strong experience with TypeScript, Experience designing and building REST APIs, Experience handling large datasets efficiently, Hands-on experience with ag-Grid, Highcharts or similar libraries, Understanding of authentication and authorization mechanisms, Experience with relational databases, Experience with performance optimization 📃 Skills: C#, .NET, ASP.NETCore, React, TypeScript, REST, ag-Grid, Highcharts, SQL, CI/CD, Authentication, Authorization, Serialization 🏢 Description: Senior Full Stack Engineer (.NET / React) Warsaw, hybrid, 3 days per week from the office. Responsibilities Build and enhance frontend applications and backend services supporting treasury workflows. Develop React/TypeScript single‑page applications and reusable UI components. Design and implement ASP.NET Core REST APIs with scalable pagination and filtering models. Optimize performance across the stack, including APIs, serialization, rendering, and large data grids. Collaborate with business stakeholders, quant teams, and product managers to deliver user‑focused solutions. Drive engineering best practices including code reviews, testing, CI/CD, and production support. Investigate production issues and improve observability and platform reliability. Mentor engineers and contribute to technical growth within the Warsaw team. Requirements 5+ years of software engineering experience building production systems. Strong experience with C#/.NET ecosystem and ASP.NET Core . Strong frontend experience with React and TypeScript. Experience building REST APIs and handling large datasets efficiently. Hands‑on experience with ag‑Grid, Highcharts, or similar UI/data visualization libraries. Strong understanding of authentication, authorization, and serialization mechanisms. Experience working with relational databases and performance optimization. Strong communication skills and ability to work directly with business stakeholders. Nice to Have Experience in treasury, trading, or financial systems. Strong product mindset and UX awareness.

🏢 Summary: Long-term remote B2B contract for a technical leader responsible for guiding a development team in building and maintaining scalable applications within an agile environment. The role combines hands-on .NET development with strategic oversight, technical analysis, and quality management. Focus is on delivering robust, cloud-oriented solutions and improving application delivery speed. 🗂️ Requirements: Proficiency in .NET and C#, Experience in full-stack development, Experience with front-end technologies, Experience with document-based databases, Knowledge of event-based messaging frameworks, Experience with cloud services, Experience with containerization, Ability to lead development team, Experience in building scalable systems 📃 Skills: .NET, C#, Angular, MongoDB, Cloud, Docker, Messaging, SQL 🏢 Description: Work model: 100% remote Start date: 30.06.2026 Rate: 160-180 PLN/h netto + VAT Contract : B2B, long-term cooperation (12-month contract up front + extensions) Recruitment process : 2 stages, including a technical test estimated to take 2-4 hours. Summary: The role focuses on leading the development team to create new solutions and maintain systems within an agile environment, emphasizing the importance of robust applications and strategic direction. Main Responsibilities: Lead the development team in creating and maintaining applications. Adopt wider technology practices and address the speed of new application delivery. Engage in hands-on development while guiding the strategic direction of projects. Collaborate with teams to gather specifications and perform technical analysis. Navigate complex systems and ensure they are built to scale. Manage developer quality and capacity amidst organizational constraints. Key Requirements: Proficient in .NET and C#. Experience with full-stack development, including front-end technologies. Familiarity with document-based databases. Knowledge of event-based messaging frameworks. Experience with cloud services and containerization. Nice to Have: Prior experience in the banking or financial services sector. Familiarity with Angular or other modern front-end frameworks. Experience with MongoDB or similar environments. Other Details: Environment: .NET, C#, Angular, MongoDB, moving towards cloud solutions. Team Structure: Full Stack Developers working closely with Business Analysts.

🏢 Summary: Technical leadership role focused on driving the development and maintenance of scalable .NET-based applications in an agile environment. The position combines hands-on full-stack development with strategic oversight of architecture, quality, and delivery speed. It involves close collaboration with cross-functional teams to build robust, cloud-oriented solutions. 🗂️ Requirements: Proficiency in .NET and C#, Experience in full-stack development, Knowledge of front-end technologies, Experience with document-based databases, Knowledge of event-based messaging frameworks, Experience with cloud services, Experience with containerization, Ability to design scalable systems, Experience leading development teams 📃 Skills: .NET, C#, Angular, MongoDB, Cloud, Docker, Kubernetes, Microservices, REST, Git 🏢 Description: Work model: 100% remote Start date: 30.06.2026 Rate: 160-180 PLN/h netto + VAT Contract : B2B, long-term cooperation (12-month contract up front + extensions) Recruitment process : 2 stages, including a technical test estimated to take 2-4 hours. Summary: The role focuses on leading the development team to create new solutions and maintain systems within an agile environment, emphasizing the importance of robust applications and strategic direction. Main Responsibilities: Lead the development team in creating and maintaining applications. Adopt wider technology practices and address the speed of new application delivery. Engage in hands-on development while guiding the strategic direction of projects. Collaborate with teams to gather specifications and perform technical analysis. Navigate complex systems and ensure they are built to scale. Manage developer quality and capacity amidst organizational constraints. Key Requirements: Proficient in .NET and C#. Experience with full-stack development, including front-end technologies. Familiarity with document-based databases. Knowledge of event-based messaging frameworks. Experience with cloud services and containerization. Nice to Have: Prior experience in the banking or financial services sector. Familiarity with Angular or other modern front-end frameworks. Experience with MongoDB or similar environments. Other Details: Environment: .NET, C#, Angular, MongoDB, moving towards cloud solutions. Team Structure: Full Stack Developers working closely with Business Analysts.