Senior Full Stack Software Engineer – C#/.NET | Medical Devices

Connexion Systems and Engineering, Inc.; Wayland (MA); Hybrid; USD 160,000 - 180,000; Full time

Job summary

Connexion Systems & Engineering is seeking a Senior Full Stack Software Engineer with strong C#/.NET expertise to develop software for medical devices. You will work across the stack, from UI to backend services, integrating with device controllers in a regulated environment.

The role requires hands-on engineering across front-end and back-end, collaboration with UX/UI, and adherence to Secure SDLC practices. Hybrid work in Northborough, MA with on-site 3 days / remote 2 days per week.

Qualifications

• 5+ years of professional full-stack development experience.
• Strong expertise in C#/.NET development.
• Experience building modern web apps with HTML/CSS/JavaScript/TypeScript.
• Knowledge of MVC/MVVM and DI patterns.
• Experience with RESTful APIs and backend services.

Responsibilities

• Design, develop, and maintain responsive web applications, backend services, and APIs using C#/.NET, HTML, CSS, JS/TS.
• Develop front-end apps with modern frameworks; Blazor is a plus.
• Build APIs and services for communication with device controllers and medical devices.
• Collaborate with UX/UI to translate wireframes into high-quality apps.
• Optimize for performance, scalability, reliability, and maintainability.
• Troubleshoot and resolve issues across front-end, back-end, and services.
• Apply OOP principles and design patterns (MVC, MVVM, DI).
• Mentor junior engineers and participate in architectural discussions.
• Work in Agile/Scrum with Git and modern workflows.
• Support regulated medical devices with IEC 62304 compliance.

Skills

C#/.NET

Front-end development

RESTful APIs

Git

Agile/Scrum

Debugging

Education

Bachelor's degree in Computer Science or related field

Tools

Blazor

Azure/AWS/Google Cloud

Job description

Title: Senior Full Stack Software Engineer – C#/.NET | Medical Devices

Hiring Organization: Connexion Systems & Engineering

Compensation, Benefits, And Employment Type

• Duration: Full-Time, Direct Hire
• Pay rate: $160,000–$180,000+ annually, DOE
• Job Location: Northborough, MA
• Work Model: Hybrid – 3 Days On-site / 2 Days Remote
• Schedule: Monday – Friday, 1st shift
• Job#: bh19871

Work Authorization & Location Requirements

• Candidates must be currently authorized to work in the United States without employer sponsorship, now or in the future.
• This position is not eligible for visa sponsorship, including employment under CPT or OPT authorization.
• Candidates must be able to work on-site in Northborough, MA, 3 days per week. Travel expenses will not be reimbursed.
• Relocation assistance is not available. Candidates must reside within commuting distance or be willing to relocate at their own expense.

Description

We are seeking an experienced Senior Full Stack Software Engineer to join a growing software engineering team developing innovative applications and connected technologies for the medical device industry.

This is an opportunity for a hands‑on engineer with strong C#/.NET expertise, modern front‑end development experience, and a solid understanding of software architecture and design principles.

The ideal candidate enjoys working across the full technology stack, from building responsive user interfaces to developing backend services and APIs that communicate with connected medical devices.

You’ll collaborate with software architects, UX/UI designers, product stakeholders, and engineering teams to develop scalable, secure, and reliable applications in a regulated environment.

Key Responsibilities

Full Stack Software Development

• Design, develop, and maintain responsive web applications, backend services, and APIs using C#/.NET, HTML, CSS, JavaScript, and/or TypeScript.
• Develop modern front‑end applications using contemporary frameworks, ideally including Blazor.
• Build and integrate APIs and services that support communication with device controllers and connected medical devices.
• Collaborate with UX/UI designers to translate wireframes, prototypes, and technical requirements into accessible, high‑quality applications.
• Optimize applications for performance, scalability, reliability, and maintainability.
• Troubleshoot and resolve complex technical issues across front‑end, backend, and service layers.

Software Engineering & Architecture

• Apply object‑oriented programming principles and established software design patterns, including MVC, MVVM, and Dependency Injection.
• Write clean, maintainable, well‑documented code while contributing to engineering standards and best practices.
• Participate in architectural discussions, technical design reviews, and code reviews.
• Mentor junior engineers and collaborate with cross‑functional development teams.
• Work within Agile/Scrum environments using Git and modern development workflows.

Medical Device Software & Cybersecurity

• Develop and maintain software supporting regulated medical devices, following applicable standards such as IEC 62304.
• Create and maintain software design documentation, traceability records, and supporting verification and validation artifacts.
• Apply secure software development lifecycle (Secure SDLC) principles, including secure coding, threat modeling, and vulnerability remediation.
• Support automated testing, continuous integration, and software quality initiatives.
• Incorporate cybersecurity best practices, including dependency management, vulnerability scanning, and software supply chain security.

Emerging Technologies & Integration

• Evaluate opportunities to incorporate AI‑enabled and agentic capabilities into software applications.
• Support emerging AI technologies, including retrieval‑augmented generation (RAG), tool calling, guardrails, and human‑in‑the‑loop workflows.
• Collaborate on integrations involving connected devices, embedded systems, and firmware interfaces.
• Stay current with emerging technologies in web development, cloud computing, application security, and AI.

Required Qualifications

• 5+ years of professional full‑stack software development experience, with a focus on front‑end applications and backend services.
• Strong hands‑on proficiency in C#/.NET development.
• Experience developing modern web applications using HTML, CSS, JavaScript, and/or TypeScript.
• Experience with modern front‑end technologies and frameworks; Blazor experience is highly desirable.
• Experience designing, developing, and integrating RESTful APIs, web services, and backend applications.
• Strong understanding of object‑oriented programming, software engineering principles, and design patterns, including MVC, MVVM, and Dependency Injection.
• Experience using Git, Agile methodologies, and Scrum development practices.
• Knowledge of software development for regulated medical devices, including IEC 62304, design controls, and requirements traceability.
• Understanding of secure coding practices, cybersecurity principles, and the Secure SDLC.
• Strong debugging, troubleshooting, and problem‑solving abilities.
• Excellent communication and collaboration skills, with the ability to work effectively across engineering disciplines.
• Bachelor’s degree in Computer Science, Software Engineering, or a related field, or equivalent professional experience.

Additional Experience Of Interest

• Blazor and other modern .NET front‑end technologies.
• Cloud platforms such as Microsoft Azure, AWS, or Google Cloud.
• Containerization, CI/CD pipelines, and automated testing frameworks.
• Medical device software verification, validation, and regulatory documentation.
• OWASP ASVS, threat modeling, dependency scanning, and software bills of materials (SBOMs).
• Connected device integration, device communication protocols, and firmware interfaces.
• Embedded development using C/C++, RTOS, or hardware‑in‑the‑loop testing.
• AI‑enabled application development, including agentic AI, RAG, tool orchestration, evaluation, and AI governance.
• Mobile application development and responsive UI/UX design.

What We’re Looking For

The successful candidate will be a strong, hands‑on C#/.NET engineer who enjoys building software across the full stack and solving complex technical challenges.

We’re particularly interested in engineers who combine modern web application development with backend service integration and an understanding of the quality, documentation, and security requirements associated with medical device software.

This role is ideal for someone who enjoys collaborating with technical teams, contributing to architectural decisions, mentoring other developers, and delivering reliable software that supports real‑world medical technologies.

Work Arrangement

This is a hybrid position based in Northborough, MA requiring 3 days on‑site and allowing 2 days of remote work each week.

Work Authorization & Location Requirements

• Candidates must be currently authorized to work in the United States without employer sponsorship, now or in the future.
• This position is not eligible for visa sponsorship, including employment under CPT or OPT authorization.
• Candidates must be able to work on‑site in Marlborough, MA, 3 days per week.
• Relocation assistance is not available. Candidates must reside within commuting distance or be willing to relocate at their own expense.

Connexion’s mission is to provide "best in class" services to job seekers. We strive to achieve excellence in job placement, staffing, and recruiting services, while treating candidates with the professionalism and respect they deserve.