Principal JavaScript/Node.js MCP Engineer

Company Description Are you passionate about building scalable AI integration platforms and defining engineering standards that impact entire organizations? We are looking for a Principal-level JavaScript/Node.js Engineer to lead the development of enterprise-wide MCP foundations and reusable platform capabilities for one of Europe’s fastest-growing FinTech products. In this role, you will combine hands-on Back-End engineering, platform architecture, and technical leadership to help multiple product teams adopt consistent MCP integration patterns. You will work with TypeScript, Node.js, distributed systems, and modern AI orchestration approaches while shaping internal engineering standards and developer experience practices. We at Sigma Software offer the opportunity to work on cutting-edge AI-enabled platform initiatives in a collaborative international environment where your technical decisions will directly influence large-scale engineering adoption and long-term platform strategy. CUSTOMER Our Customer is one of Europe’s fastest-growing FinTech companies, delivering a comprehensive financial infrastructure platform for businesses. The company provides embedded financial services, including virtual cards, bank transfers, account management, and payment operations through scalable APIs and modern financial technology solutions. Operating in a high-scale and rapidly evolving environment, the Customer places strong emphasis on engineering excellence, platform scalability, and architectural consistency. PROJECT The project focuses on building the engineering foundations for enterprise-wide MCP adoption across multiple product teams. The goal is to establish shared architecture standards, reusable TypeScript/Node.js libraries, SDKs, templates, and development practices that enable teams to build scalable MCP-compatible integrations consistently. As a Principal JavaScript/Node.js MCP Engineer, you will drive platform architecture decisions, define engineering standards, and build reusable tooling for MCP servers, agent orchestration, context management, authentication, and integration workflows. The role also includes defining architectural guidance for MCP, A2A communication, APIs, and service-to-service integrations while helping scale AI integration expertise across the organization. Key Technologies: TypeScript, JavaScript, Node.js, AWS, MCP, LLM Integrations, APIs, Distributed Systems, SDK Development, Microservices, AI Orchestration. Job Description Design and implement core MCP platform capabilities, including MCP clients, servers, tool invocation workflows, and integrations with existing backend servicesDefine reusable reference architectures, engineering standards, and development patterns for MCP-compatible systemsBuild shared TypeScript/Node.js libraries, SDKs, starter kits, templates, and tooling that accelerate adoption across engineering teamsDesign scalable approaches for conversation state management, agent orchestration, context handling, authentication, and versioningEstablish architectural guidelines for selecting appropriate integration patterns, including MCP, A2A, APIs, and service-to-service communicationCollaborate with multiple engineering teams to review technical designs, ensure consistency, and drive platform adoptionCreate technical documentation, best practices, and onboarding materials for developers working with MCP integrationsMentor engineers and provide technical leadership across platform and backend initiativesContribute to long-term platform scalability, maintainability, and engineering governance Qualifications At least 7 years of production experience with JavaScript, TypeScript, and Node.jsExtensive experience in Back-End or platform engineering, including technical leadership at Principal or Staff levelProven expertise in designing distributed systems, APIs, SDKs, developer platforms, or Back-End frameworksDeep understanding of scalable architecture design, interface contracts, versioning strategies, and reusable platform componentsHands-on experience with MCP clients, servers, resources, tools, and LLM tool invocation patternsExperience building AI-enabled platforms or LLM-based integrationsKnowledge of Developer Experience best practices and internal platform engineeringExperience driving technical initiatives across multiple engineering teams and stakeholdersExperience defining enterprise engineering standards and governance modelsAbility to balance strategic architectural thinking with hands-on implementationExperience working in cloud-native and microservice-based environmentsAt least an Upper-Intermediate level of English WILL BE A PLUS Experience with Agent-to-Agent communication and orchestration frameworksFamiliarity with FinTech or regulated environmentsExperience designing reusable SDKs or integration frameworks Additional Information PERSONAL PROFILE Strong technical leadership and ownership mindsetExcellent collaboration and cross-team communication skillsAbility to drive engineering alignment in complex organizationsProactive problem solver with strategic thinking capabilitiesPassion for platform engineering, developer enablement, and scalable architectureComfortable operating in fast-paced and evolving technical environments