Senior Full Stack Software Engineer

WEX•Boston, MA

38d•$120,000 - $160,000•Remote

About The Position

WEX is a global leader in financial technology solutions, simplifying complex payment ecosystems across Fleet, Corporate Payments, and Benefits. We are driving a major transformation through Helix—a technology strategy to modernize our platforms, accelerate innovation, and deliver exceptional customer experiences. We are seeking a Full Stack Software Engineer (Level 3) who can design and deliver scalable, secure, and modular systems that align with Helix’s pillars: workflow optimization, payments intelligence, and industry expertise. This role offers the opportunity to shape our next-generation platforms while modernizing legacy systems into API-first, composable, and data-driven architectures.

Requirements

Bachelor’s degree in Computer Science, Engineering, or equivalent experience.
5+ years in backend/microservices development (Python, Java, Node.js, etc)
3+ years building RESTful APIs; experience with event streaming (Kafka).
Strong knowledge of CDC, JSON/XML, relational/NoSQL, Postgres and other modern databases.
Experience in Unix/Linux environments, scripting, and CI/CD pipelines.
Demonstrated ability to decompose systems into modular, reusable services.
Excellent communication and collaboration skills across distributed teams.

Nice To Haves

Experience with FinTech platforms or payments ecosystems.
Exposure to Siebel CRM or other enterprise systems, particularly in integration.
Cloud experience (AWS preferred), containerization (Docker, Kubernetes).
Familiarity with modern UI frameworks (React, Angular, Vue.js).
Understanding of AI/ML integration in platforms and workflows.
Experience with large-scale transaction or high-availability systems.

Responsibilities

Lead design and development of full-stack solutions, with emphasis on event-driven microservices, APIs, and data platforms.
Drive iterative modernization, helping decompose monoliths into shared, modular services.
Build reusable capabilities aligned with product-centric domain models.
Contribute to agentic architectures and intelligent automation that power seamless user experiences.
Collaborate with cross-functional teams to deliver measurable business outcomes, not just features.
Mentor junior developers and promote Helix-aligned engineering practices.
Design, develop, test, and maintain cloud-ready services and APIs.
Work with streaming data pipelines (Kafka, CDC, JSON) to enable real-time insights.
Implement platform-thinking approaches—build reusable, discoverable capabilities.
Ensure quality from the start through automated validation and CI/CD pipelines.
Deliver value iteratively, focusing on finishing and deploying features, not just starting them.
Partner with product and architecture teams to ensure systems are decoupled, scalable, and SaaS-mature.
Use monitoring and feedback loops to drive data-informed improvements.
Tackle technical debt proactively, balancing modernization with customer value delivery.