Sr Software Engineer (React, JavaScript, .net)

Fiserv•Hagerstown, MD

1d•$90,000 - $127,000•Onsite

About The Position

Join the Client Services technology team as a Full-Stack Web Developer to build and enhance the high-value, data-driven applications that power our global support operations. In this role, you will work across a modern tech stack—utilizing React and TypeScript on the front end alongside C# and ASP.NET Core on the back end—to turn complex business data workflows into secure, scalable, and intuitive user experiences. By partnering with cross-functional business and technical teams, your engineering output will directly improve operational readiness, speed-to-market, and the overall efficiency of our client-facing services ecosystem.

Requirements

Bachelor’s degree in Computer Science, Management Information Systems (MIS), or equivalent practical/professional work experience.
5+ years of professional hands-on experience designing, building, delivering, and supporting full-stack web applications.
Strong backend proficiency in C# and modern .NET development (ASP.NET Core).
Strong frontend proficiency in React utilizing modern patterns, including functional components, custom hooks, and component design.
Production experience using TypeScript and modern JavaScript (ES6+) alongside HTML5 and CSS3 with an awareness of responsive layouts and accessibility.
Solid database expertise with SQL Server and T-SQL, including data modeling, advanced querying, and schema optimization.
Proven experience building, securing, and consuming REST APIs for client-device and web-client interactions.
Familiarity with modern software development practices, including Git-based version control (advanced branching and merging), CI/CD concepts, automated unit/integration testing, and log-based production troubleshooting.
Excellent written and verbal communication skills with the ability to work cross-functionally and translate business requirements into software solutions.

Nice To Haves

Experience utilizing Entity Framework Core or an equivalent Object-Relational Mapping (ORM) framework.
Practical experience implementing authentication and authorization standards (e.g., OAuth2, JWT, or Microsoft Entra ID).
Familiarity with containerization (Docker) and deploying workloads across cloud ecosystems (Azure/AWS) or hybrid/on-prem environments.
Knowledge of asynchronous messaging patterns, queuing architectures, and background processing jobs.
Exposure to enterprise reporting, data analysis, or embedded analytics tools such as SSRS or Power BI.
Previous engineering experience within the payments, fintech, or financial services industries.
Comfort working with modern engineering tooling, including Visual Studio/VS Code, SSMS, Azure DevOps, GitHub Actions, or IIS.

Responsibilities

Design, develop, and maintain responsive web applications using React and ASP.NET Core to support modern Single Page Application (SPA) experiences.
Build, evolve, and support robust RESTful APIs and backend microservices in C# with a strong emphasis on maintainability, scalability, and clean architecture.
Translate complex business needs into well-structured technical solutions, including UI workflows, API contracts, and performant data models.
Develop, optimize, and maintain SQL Server database schemas, T-SQL queries, stored procedures, and advanced indexing strategies to support high-volume data use cases.
Implement enterprise-grade security practices, including secure coding patterns, robust authentication/authorization protocols, and least-privilege access controls.
Create reusable, tested front-end components and backend services using modular design patterns that facilitate long-term codebase health.
Collaborate closely with product owners, technical analysts, and cross-functional support teams to reliably deliver features from concept and build to release and support.
Participate actively in code reviews, system troubleshooting, performance tuning, and production monitoring to ensure top-tier software quality.
Contribute to essential technical documentation, including design notes, operational runbooks, and supportability guides to enhance team velocity.

Benefits

Fuel Your Life program to support your physical, financial, social, and emotional well-being
Paid holidays and generous time away policies
No-cost mental health support through Employee Assistance Programs
Living Proof program to recognize your peers’ extra effort with points redeemable for rewards
Eight Employee Resource Groups to foster a collaborative culture and expand your network
Unparalleled professional growth with training, development, and internal mobility opportunities
Medical, dental, vision, life, and disability insurance options available from day one
Retirement planning and discounted shares with the Employee Stock Purchase Plan
Tuition assistance and reimbursement program
Paid parental, caregiver, and military leave