Staff Engineer

WEX Inc; California; Hybrid; USD 141,000 - 173,000; Full time

Benefits offered by this job

Health, dental and vision insurance

Retirement savings plan

Paid time off

Health savings account

Flexible spending accounts

Life insurance

Disability insurance

Tuition reimbursement

Job summary

WEX Inc. is seeking a Staff Software Engineer to architect and lead platform changes for the Digital Credit Application, moving from a legacy monolith to a cloud-native microservices architecture.

You will decouple core adjudication logic, enable rapid A/B testing, and lay the foundation for AI-driven decisioning and chat interfaces. You will champion Strangler Fig migration, modular adjudication, and an API-first design while promoting observability, CI/CD, and strong technical mentorship

Qualifications

• 10+ years of backend architecture experience, Fintech/Lending context preferred.
• Proficient in Java 17/21, Spring Boot 3.x, and Spring Cloud.
• Experience migrating from legacy monoliths to distributed microservices (AWS).
• Strong experience with event-driven design using Kafka or RabbitMQ.
• Experience designing API contracts with OpenAPI/Swagger.
• Proficiency with AI-assisted development tools to accelerate delivery.
• Excellent communication and leadership across cross-functional teams.

Responsibilities

• Lead the architectural migration from a legacy monolith to a scalable microservices backbone.
• Design a pluggable adjudication layer and a versioned API ecosystem.
• Drive AI readiness and adoption across the delivery lifecycle.
• Provide technical mentorship to engineers and uphold high coding standards.

Skills

Backend architecture

Java 17/21

Spring Boot 3.x

Monolith to microservices

Kafka/RabbitMQ

API contracts (OpenAPI/Swagger)

AI tooling (Cursor/Copilot)

Leadership & mentorship

Education

Bachelor’s degree in Computer Science or related field

Tools

OpenTelemetry

GitHub Copilot

Cursor

Spring Cloud

Job description

About the team / Role: As a Staff Software Engineer, you will be the primary architect and execution lead for leading the platform changes for the Digital Credit Application. We are pivoting from a legacy 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 true "builder" who thrives on the duality of supporting a live production environment while aggressively migrating mission-critical services to a modern, microservices-based backbone. You will encounter varied customer scenarios where your out-of-the-box approach is a better fit than standard industry practices. We expect you to make a true difference for the customer, leveraging technology and AI to best serve and solve for good.

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.

The AI Edge

We are a forward-thinking engineering org. You are expected to be an expert in leveraging AI Software Development Lifecycle (ADLC) tools (e.g., GitHub Copilot, Cursor, Amazon Q, LLM-based code gen and architecture agents) to accelerate migration, write bulletproof tests, and automate documentation.

Architectural Migration & Strategy

Strangler Fig Migration: Lead the decoupling of core credit application logic out of the legacy monolith and into a scalable, cloud-native Java/Spring Boot micro services environment. Migration with Zero Downtime: Design and execute high-volume traffic migration strategies from legacy systems to new stacks seamlessly without disrupting live customers.

Pluggable Adjudication & API Ecosystem

Modular Architecture: Design and implement a modular adjudication layer allowing the business to swap or update credit rules and third-party data providers without impacting core application flows. API-First Design: 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 backend infrastructure for dynamic routing and experimentation, allowing real-time testing of various application flows.

AI Readiness & Process Acceleration

AI DLC Mastery: Champion the use of AI tools across the development lifecycle to write code faster, refactor legacy code into modern Java, and generate robust test suites. Data Science Partnership: Partner with Data Science teams to ensure data pipelines and backend schemas are optimized for LLM integration and real-time credit decisioning models.

Operational Excellence & Leadership

Observability & CI/CD: Establish rigorous standards for CI/CD, observability (OpenTelemetry), and automated contract testing. Technical Mentorship: Provide guidance to mid-level and senior engineers, fostering a culture of high engineering standards, clean code, and AI-assisted productivity.

Experience you will bring

• Technical Architecture & Stack: 10+ Years of Engineering Excellence: Proven track record in backend architecture, specifically within Fintech, Lending, or Credit systems.
• Modern Java Stack: Expert-level proficiency in Java 17/21, Spring Boot 3.x, and Spring Cloud.
• Monolith-to-Distributed Migration: Significant experience extracting tightly coupled business logic from legacy backends into external, scalable cloud microservices (AWS).
• 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 asynchronous data consistency between the new API layer and legacy systems of record during migration phases.
• Contract-First Development: Strict adherence to API contracts (OpenAPI/Swagger) to ensure seamless collaboration with frontend teams.
• AI & Modern Delivery Tools: AI DLC Proficiency: Hands-on experience using AI coding assistants (Cursor, Copilot, etc.) to optimize workflows, refactor legacy code, and accelerate delivery.
• Leadership & Education: Strong analytical skills and a proven capability in resolving complex, cross-functional problems. Excellent written and verbal communication skills; ability to present complex technical concepts clearly to stakeholders. Bachelor’s degree in Computer Science or a related technical 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.

Pay Range

Pay Range: $140,600.00 - $173,100.00 WEX is a global commerce platform that helps businesses solve for operational complexities like employee benefits, managing and mobilizing fleets, and streamlining payments. With over 6,500 employees, we work with large and small companies in more than 200 countries and territories, and can tailor our services to meet the unique needs of their businesses. We hire people who share our passion for continuous innovation and client service that is unparalleled in the industry.

Diversity & Inclusion

WEX is an equal opportunity employer committed to diversity and inclusion in the workplace. All qualified applicants will receive consideration for employment without regard to sex, race, color, age, national origin, religion, sexual orientation, gender identity, protected veteran status, disability or other protected status. WEX promotes a drug-free workplace. Qualified individuals with a disability have the right to request a reasonable accommodation. If you require a reasonable accommodation as a result of your disability at any point in the job application process, please submit your request through our Reasonable Accommodation Request Form. This form is for accommodation requests only and cannot be used to inquire about the status of applications.