Fullstack Integration Engineer

Senior Full-Stack Integration Engineer

Location: Remote – United States

Experience: 5+ years of professional software engineering experience

We are seeking a Senior Full-Stack Integration Engineer to design, build, and support cloud-based applications, APIs, and external partner integrations. This position is best suited for a backend-leaning full-stack engineer with strong experience in Node.js, TypeScript, React, AWS, and production database environments.

The ideal candidate will have hands-on experience developing partner-facing APIs, integrating third-party systems, and building reliable cloud services used by external customers and business partners.

Responsibilities

• Design, develop, test, and maintain backend services using Node.js and TypeScript

• Build and enhance frontend application features using React and TypeScript

• Design and develop REST and/or GraphQL APIs for use by external partners

• Integrate applications with third-party platforms, vendors, and partner systems

• Build and operate cloud-based services within AWS

• Develop serverless applications using services such as AWS Lambda and API Gateway

• Design and maintain production data models using relational or document databases

• Collaborate with product, engineering, and external partner teams to define integration requirements

• Troubleshoot API, data, and integration issues across distributed systems

• Participate in code reviews, testing, deployment, and ongoing application support

• Help establish scalable development practices for partner integrations and cloud services

Required Qualifications

• 5+ years of professional software engineering experience

• Strong backend development experience with Node.js

• Advanced TypeScript experience across backend and frontend applications

• Professional frontend development experience using React

• Production experience with a relational or document database, preferably PostgreSQL or MongoDB

• Experience building and operating applications or services within AWS

• Hands-on experience integrating with third-party or external partner systems

• Experience designing and developing externally consumed REST and/or GraphQL APIs

• Strong understanding of API security, authentication, error handling, and data validation

• Ability to work effectively in a remote, collaborative engineering environment

Preferred Qualifications

• Experience with NestJS

• Production experience with MongoDB

• Experience developing GraphQL APIs

• Experience with AWS serverless technologies, including Lambda and API Gateway

• Previous government or public-sector delivery experience

• Experience supporting applications with multiple external partner integrations

• Familiarity with automated testing, CI/CD pipelines, monitoring, and production support

This is a remote opportunity available to candidates located within the United States.

System One, and its subsidiaries including Joulé and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.

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