Note: The job is a remote job and is open to candidates in USA. WEX is a company focused on platform technology, and they are seeking a Senior Software Engineer, AI-Augmented Backend to modernize legacy systems. The role involves designing complex backend services, migrating legacy functionality, and ensuring high availability in a payments environment.
Responsibilities
- Own the design and implementation of complex backend services in Java and Spring Boot, from architecture through production rollout and operability
- Drive the incremental migration of legacy functionality toward REST using the Strangler pattern
- Design event-driven data flows (CDC pipelines, schema evolution, idempotent consumers) that keep distributed systems consistent under load
- Make and document consequential architecture decisions: API contracts, data models, consistency and transactional boundaries, failure modes, and rollback strategy
- Practice spec-driven development: define clear, machine-readable contracts and specifications (e.g., OpenAPI, schema definitions, RFC 9457 problem formats) before implementation, so that designs are unambiguous, reviewable, and consumable by both humans and AI agents
- Use AI-assisted development tooling effectively and responsibly — leveraging coding assistants and agentic workflows to accelerate delivery while owning correctness, review, and the security implications of generated code
- Own service availability and reliability: design for high availability, define and defend SLOs/error budgets, plan for graceful degradation and failover, and participate in on-call to keep critical payment paths healthy
- Build observability in from the start, not as an afterthought — instrument services with metrics, distributed tracing, and structured logging (OpenTelemetry / Micrometer), and use that telemetry to drive alerting, SLOs, and incident diagnosis
- Set the standard for code quality, testing, and operational readiness, and raise that standard through code review, design review, and technical mentorship of other engineers
- Build for a payments environment: handle sensitive cardholder data responsibly, design with PCI DSS requirements in mind, and bake in audit logging and least-privilege access from the start
- Diagnose and resolve performance and reliability issues across the stack — query optimization, caching strategy, indexing, connection management, and latency under real production traffic
- Partner with product, platform, and other engineering teams to break large initiatives into safe, shippable increments
Skills
- 7+ years of professional software engineering experience, with a strong track record of building and operating backend services in production
- Deep expertise in Java and the Spring / Spring Boot ecosystem
- Strong command of relational databases — data modeling, query optimization, indexing, and transaction management
- Demonstrated experience designing and evolving RESTful APIs (versioning, error semantics, idempotency, backward compatibility)
- Hands-on experience with distributed and/or event-driven systems (e.g., Kafka or similar messaging/streaming platforms)
- Solid grounding in system design: you can reason about consistency, fault tolerance, scalability, and operational trade-offs, and communicate those trade-offs clearly
- Strong observability practice — you instrument services with metrics, distributed tracing, and structured logging using OpenTelemetry, Prometheus, and Grafana, and use that telemetry to define alerts, diagnose incidents, and understand production behavior
- Experience operating high-availability services: defining and meeting SLOs, designing for failover and graceful degradation, and supporting production systems through on-call
- Comfort with spec-driven development — designing against explicit contracts (OpenAPI, schemas, well-defined error formats) before writing code
- Effective, judicious use of AI-assisted development tools (spec driven development, skills), with clear ownership of the correctness, quality, and security of the resulting code
- A demonstrated security mindset — you think about data protection, safe credential handling, and injection / input-validation risks by default
- Strong written and verbal communication; able to influence technical direction across a team without formal authority
- Working knowledge of Domain-Driven Design (aggregates, bounded contexts, application services)
- Experience with AWS and Kubernetes (EKS), HashiCorp Vault, and Redis-compatible caching at scale
- Must be authorized to work in the United States without sponsorship
- Experience modernizing legacy systems, particularly with the Strangler pattern or comparable incremental-migration approaches
- Familiarity with Change Data Capture (e.g., Debezium) and schema-registry-backed event pipelines (Avro/Protobuf)
- Experience in payments, fintech, or other regulated, high-compliance domains (PCI DSS exposure a plus)
- Experience with legacy migrations off Informix or comparable enterprise RDBMS platforms
- Performance / load testing experience (e.g., k6) and capacity planning
- Proven track record with AI-driven development platforms such as Claude Code, Cursor, Augment, and GitHub Copilot
Benefits
- Health, dental and vision insurances
- Retirement savings plan
- Paid time off
- Health savings account
- Flexible spending accounts
- Life insurance
- Disability insurance
- Tuition reimbursement
Company Overview