[Remote] Senior Backend Engineer – AI Platform

Note: The job is a remote job and is open to candidates in USA. WEX Inc. is a company focused on mobility solutions, and they are seeking a Senior Backend Engineer to join their Platform team. This role involves designing and developing AI platforms to support feature development, enabling robust and scalable solutions for autonomous AI agents and complex workflows in the fintech space.ResponsibilitiesDesign, develop, and maintain robust, scalable, and high-performance object oriented code in our backend servicesDevelop public REST APIs using Java and internal gRPC APIs for inter-service and inter-system communicationCraft systems designs, lead design decisions, and drive alignment with other senior engineersWrite automated unit tests, integration tests, end-to-end tests, concurrency tests, load/performance testsAnalyze existing systems to identify bottlenecks, tech debt, and implement scalability, and stability improvementsImplement automation for testing, monitoring, healing, and scaling applications, continuous integration and deployment to reduce time to marketCollaborate with cross-functional teams, including product managers, designers, and other engineers, to define and implement new featuresConduct code reviews (comment, approve, seek revisions, merge), mentor junior and mid-level engineers, and actively promote engineering best practicesDive deep and troubleshoot complex issues, devise fixes, author root cause analysis documents, and ensure lasting performance and reliabilityConduct objective and comparative analyses of competing technologies to advise the team of pros and cons of a technology solutionMaintain robust documentation (design docs, run books, change management docs, and readiness plans)Provide live-site support for production applications by monitoring systems, ensuring rapid incident resolution, and driving continuous improvementDrive cross-team projects as a single-threaded-owner (STO) or tech lead, and actively unblock other engineers to make progressDesign and build agentic AI systems and services, enabling autonomous workflows, reasoning, and task execution within Mobility platformsDevelop AI agents from scratch, including orchestration, tool usage, memory, and multi-step decision-making capabilitiesImplement and scale multi-agent architectures to support complex, distributed use cases across payments and fleet ecosystemsIntegrate systems using Model Context Protocol (MCP) or similar frameworks to enable secure and scalable interaction between AI agents, APIs, and enterprise data sourcesBuild and optimize LLM-powered services (e.g., OpenAI APIs, LangChain) for production-grade performance, reliability, and cost efficiencyImplement evaluation frameworks, observability, and guardrails to ensure correctness, safety, and compliance of AI-driven systemsDesign solutions for context management, memory, and retrieval-augmented generation (RAG) to enhance agent effectivenessSkillsBachelor's degree in Computer Science or Software Engineering5–8 years of professional experience in software engineeringStrong understanding of data structures and algorithms, object-oriented design, and problem-solving skillsExpertise in designing and developing internet-scale services with scalability, availability, security, and reliability design tenetsExcellent written and verbal communication skills, and a collaborative and empathetic mindsetProficiency in backend development, with expertise in Java or C#, frameworks like SpringBoot, building and optimizing RESTful APIs, ODATA framework, and SQLHands-on experience building or contributing to AI/LLM-powered applications or agent-based systemsFamiliarity with agent frameworks, tool-use patterns, and orchestration of LLM workflowsExperience integrating AI systems with external tools/APIs using MCP or similar protocolsUnderstanding of prompt engineering, embeddings, and vector-based retrieval systemsExperience designing systems for scaling AI workloads in production environmentsMaster's degree in computer science or software engineering8+ years of experience in software engineeringExperience with Python, Java, event-driven architecture and tools like KafkaExperience working on card paymentsFamiliarity with cloud-native architecture (containerization using tools such as Docker and Kubernetes)Awareness of API security and PCI DSS compliance requirementsAbility to work on existing codebase, contribute improvements, and adapt to legacy systems' constraintsExperience building AI skills & deploying AI solutions to production environmentsExperience building production-grade AI agents or copilotsFamiliarity with multi-agent systems and distributed AI architecturesExperience with vector databases (e.g., Pinecone, Weaviate, OpenSearch, Milvus)Knowledge of AI evaluation techniques, safety practices, and responsible AI principlesBenefitsCommission under the terms of an applicable plan for most sales positionsQuarterly or annual bonus based on their role and applicable plan for non-sales rolesHealth, dental and vision insurancesRetirement savings planPaid time offHealth savings accountFlexible spending accountsLife insuranceDisability insuranceTuition reimbursementCompany OverviewWex is a financial technology service provider for fleet, travel and healthcare industries. It was founded in 1983, and is headquartered in Portland, Maine, USA, with a workforce of 5001-10000 employees. Its website is http://www.wexinc.com.Company H1B SponsorshipWEX has a track record of offering H1B sponsorships, with 4 in 2026, 22 in 2025, 10 in 2024, 12 in 2023, 20 in 2022, 14 in 2021, 18 in 2020. Please note that this does not guarantee sponsorship for this specific role.