This is a remote position; however, the candidate must reside within 30 miles of one of the following locations: Portland, ME; Boston, MA; Chicago, IL; Dallas, TX; San Francisco Bay Area, CA; and Seattle/WA.

As a Staff Backend Engineer, you will be the primary architect and execution lead for the transformation of our Digital Credit Application. We are pivoting from a Salesforce-centric monolith to a high-performance, pluggable API ecosystem. Your mission is to decouple core adjudication logic, enable rapid A/B testing of the customer journey, and lay the technical foundation for future AI-driven chat and automated decisioning experiences.

This is a high-impact role designed for a "builder" who can manage the duality of supporting a live Salesforce environment while aggressively migrating mission-critical services to a modern, micro services based backbone.

Core Responsibilities

• Architectural Migration: Lead the "Strangler Fig" migration of credit application logic out of Salesforce and into a scalable, cloud-native Java/Spring Boot microservices environment.

• Pluggable Adjudication: Design and implement a modular adjudication layer that allows the business to swap or update credit rules and third-party data providers without impacting the core application flow.

• API-First Ecosystem: Build and maintain robust, versioned REST/gRPC APIs that support a multi-channel experience (Mobile, Web, and future AI Chat interfaces).

• A/B Strategy Enablement: Engineer the backend infrastructure to support dynamic routing and experimentation, allowing Product teams to test various application flows and UI treatments in real-time.

• Operational Excellence & Ownership: Transition the platform by establishing rigorous standards for CI/CD, observability (OpenTelemetry), and automated testing.

• AI Readiness: Partner with Data Science teams to ensure data pipelines and backend schemas are optimized for LLM integration and real-time credit decisioning models.

• Provide technical mentorship and guidance to mid-level and senior engineers, fostering a culture of high engineering standards.

Key Qualifications:

• 10+ Years of Engineering Excellence: Proven track record in backend architecture, specifically within Fintech, Lending, or Credit systems.

• Salesforce Integration Mastery: Significant experience integrating Salesforce with external AWS/Cloud microservices. You understand how to extract business logic from Apex/Flows into external services.

• Modern Java Stack: Expert-level proficiency in Java 17/21, Spring Boot 3.x, and Spring Cloud.

• Complex Adjudication & Rules Engines: Experience building or implementing rules engines (e.g., Drools, Camunda, or custom JSON-logic) for automated decisioning.

• Event-Driven Design: Deep experience with Kafka or RabbitMQ for maintaining data consistency between the new API layer and legacy systems of record.

• Contract-First Development: Strong belief in API contracts (OpenAPI/Swagger) to ensure seamless collaboration with frontend and mobile teams.

• Migration Strategy: Demonstrated ability to migrate high-volume traffic from legacy systems to new stacks with zero downtime.

• Excellent analytical skills and capability in identifying and resolving complex, cross-functional problems.

• Strong written and verbal communication skills, able to present complex technical concepts clearly.

• Bachelor's degree in Computer Science or a related field.

The base pay range represents the anticipated low and high end of the pay range for this position. Actual pay rates will vary and will be based on various factors, such as your qualifications, skills, competencies, and proficiency for the role. Base pay is one component of WEX's total compensation package. Most sales positions are eligible for commission under the terms of an applicable plan. Non-sales roles are typically eligible for a quarterly or annual bonus based on their role and applicable plan. WEX's comprehensive and market competitive benefits are designed to support your personal and professional well-being. Benefits include health, dental and vision insurances, retirement savings plan, paid time off, health savings account, flexible spending accounts, life insurance, disability insurance, tuition reimbursement, and more. For more information, check out the "About Us" section.Pay Range: $140,600.00 - $173,100.00