Staff Software Engineer, Backend & APIs

WEX, Inc.; Seattle (WA); On-site; USD 141,000 - 173,000; Full time

Job summary

WEX, Inc. is seeking a Staff Software Engineer to design, develop, and operate scalable backend services powering our mobile and web apps. You will work with product, platform, and security teams to deliver robust APIs and distributed systems that drive exceptional customer experiences.

You will lead architecture discussions, optimize databases, and implement automated testing and observability. You will mentor engineers and help improve engineering practices while advancing CI/CD pipelines and

Qualifications

• Bachelor's degree in Computer Science, Software Engineering, or a related field.
• 8-10 years of professional software engineering experience.
• Strong expertise in Java and Spring Boot for enterprise-grade backend apps.
• Experience designing RESTful APIs and distributed microservices.
• Strong understanding of OO design, data structures, algorithms, and design principles.
• Experience with PostgreSQL or other relational DBs, including schema design and indexing.
• Experience building scalable, secure, highly available distributed systems.
• Understanding of authentication/authorization, API security, OAuth2/JWT, and secure dev practices.
• Experience with asynchronous messaging (Kafka, RabbitMQ).
• Familiarity with Redis and distributed caching strategies.
• Experience with CI/CD, automated testing, and code quality tools.
• Strong observability knowledge (logging, metrics, tracing, monitoring, alerting).
• Experience collaborating with mobile teams and API design for iOS/Android.
• Excellent communication, collaboration, mentoring, and leadership skills.
• Hands-on experience using AI coding assistants and tools.

Responsibilities

• Design, develop, and maintain scalable, secure backend services using Java, Spring Boot, PostgreSQL, and REST APIs.
• Architect and build distributed microservices that are resilient, observable, and maintainable.
• Design REST APIs for mobile, web, and partner integrations.
• Lead architecture discussions and produce design docs.
• Optimize database design, queries, and indexing for performance.
• Develop automated testing strategies including unit, integration, and performance tests.
• Improve reliability with observability, logging, tracing, and health monitoring.
• Identify bottlenecks and drive platform improvements.
• Build and enhance CI/CD pipelines and deployment automation.
• Collaborate with Product, Mobile, Web, Security, and DevOps teams.
• Lead code reviews, mentor engineers, and raise engineering quality.
• Troubleshoot production issues and perform root cause analysis.
• Evaluate emerging technologies and provide technical recommendations.
• Create architecture docs, API specs, runbooks, and readiness plans.
• Design highly available services with retries, circuit breakers, caching, and rate limiting.
• Drive cross-functional initiatives as technical lead or STO.
• Gain hands-on with automation and AI-assisted software engineering.

Skills

Java

Spring Boot

REST APIs

Distributed systems

PostgreSQL

OAuth2/JWT

Kafka/RabbitMQ

CI/CD

Observability

Mentoring

Education

Bachelor's degree in Computer Science / Software Engineering

Tools

AWS

Kubernetes

Docker

Terraform

OpenTelemetry

Job description

About the Team/Role

We're looking for a Staff Software Engineer with deep expertise in backend development to join our 10-4 by WEX team. You will play a key role in designing, developing, and operating highly scalable, secure, and resilient backend services that power our mobile and web applications. You will work closely with mobile, web, product, and platform engineering teams to deliver APIs and distributed systems that provide seamless customer experiences.

Our platform helps owner-operators and small fleets save money on fuel through one of the industry's largest fuel discount networks. The mobile application enables truck drivers to discover participating fuel locations, activate discounts, manage payment methods, view transaction history, and access real-time fuel pricing and savings. As a Staff Software Engineer, you'll build the backend services and APIs that power these experiences, ensuring they are secure, scalable, highly available, and capable of supporting a growing user base while delivering a reliable and seamless experience for drivers on the road.

How you'll make an impact

• Design, develop, and maintain scalable, secure, and high-performance backend services using Java, Spring Boot, PostgreSQL, and REST APIs.

• Architect and build distributed microservices that are resilient, observable, and easy to maintain.

• Design REST APIs that enable seamless integration with mobile applications, web applications, and external partner systems.

• Lead architecture and system design discussions, producing high-quality design documents and driving alignment across engineering teams.

• Optimize database design, queries, indexing strategies, and transaction management to improve performance and scalability.

• Develop comprehensive automated testing strategies, including unit, integration, contract, performance, and load testing.

• Improve application reliability by implementing observability, logging, distributed tracing, health monitoring, and alerting.

• Identify technical debt, scalability bottlenecks, and reliability risks, and drive continuous platform improvements.

• Build and enhance CI/CD pipelines, deployment automation, infrastructure automation, and engineering productivity tools.

• Partner closely with Product, Mobile, Web, Security, Infrastructure, and DevOps teams to deliver high-quality customer experiences.

• Lead code reviews, mentor engineers, establish engineering best practices, and raise the overall quality bar across the organization.

• Troubleshoot complex production issues, perform root cause analysis, implement corrective actions, and improve operational excellence.

• Evaluate emerging technologies and architectural approaches, providing technical recommendations based on business and engineering needs.

• Create and maintain technical documentation including architecture documents, API specifications, runbooks, operational guides, and readiness plans.

• Design highly available services with appropriate resilience patterns including retries, circuit breakers, caching, rate limiting, and graceful degradation.

• Drive cross-functional initiatives as a technical lead or Single-Threaded Owner (STO), helping unblock teams and ensuring successful delivery.

• Gain hands-on experience with automation and AI-assisted software engineering solutions.

Experience you'll bring

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

• 8-10 years of professional software engineering experience.

• Strong expertise in Java and Spring Boot for building enterprise-grade backend applications.

• Experience designing and developing RESTful APIs and distributed microservices.

• Strong understanding of object-oriented design, data structures, algorithms, and software design principles.

• Experience with PostgreSQL or other relational databases, including schema design, query optimization, indexing, and transaction management.

• Experience building scalable, secure, highly available, and fault-tolerant distributed systems.

• Strong understanding of authentication, authorization, API security, OAuth2, JWT, and secure software development practices.

• Experience with asynchronous messaging technologies such as Kafka, RabbitMQ, or similar event-driven platforms.

• Familiarity with caching technologies such as Redis and distributed caching strategies.

• Experience with CI/CD pipelines, automated testing, code quality tools, and modern software delivery practices.

• Understanding of observability technologies including logging, metrics, tracing, monitoring, and alerting.

• Experience collaborating with mobile engineering teams and designing APIs optimized for iOS and Android applications.

• Excellent communication, collaboration, mentoring, and technical leadership skills.

• Hands-on experience leveraging AI coding assistants and development tools (e.g., GitHub Copilot, Cursor, Claude) to accelerate software development, refactoring, and code generation.

Preferred Qualifications

• Master's degree in Computer Science or Software Engineering.

• 10+ years of software engineering experience.

• Experience with cloud-native application development using AWS, Kubernetes, Docker, and Terraform.

• Experience with API Gateways, service mesh technologies, and cloud networking concepts.

• Experience with event-driven architectures and distributed systems patterns.

• Familiarity with OpenTelemetry, Grafana, Prometheus, or similar observability platforms.

• Exposure to mobile application development (Android and/or iOS) with an understanding of mobile architecture, API consumption patterns, offline synchronization, and application performance considerations.

• Experience leading technical initiatives across multiple engineering teams and mentoring senior engineers.

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