Principal JavaScript/Node.js MCP Engineer (FinTech Project)

Sigma Software; Poland; On-site; PLN 240,000 - 360,000; Full time

Job summary

Sigma Software is seeking a senior Backend/Platform engineer to lead MCP platform adoption across product teams. You will shape standards, build reusable TypeScript/Node.js libraries, and mentor engineers while advancing AI-enabled platform initiatives.

You will influence architectural decisions, define integration patterns, and collaborate with multiple teams to ensure consistent MCP implementations and scalable backend solutions.

Qualifications

• Extensive backend/platform engineering experience with technical leadership at Principal or Staff level.
• Deep understanding of scalable architecture, interface contracts, versioning, and reusable components.
• Hands-on experience with MCP clients/servers and LLM tool invocation patterns.
• Experience building AI-enabled platforms or LLM-based integrations.
• Knowledge of Developer Experience best practices and internal platform engineering.
• Experience driving initiatives across multiple engineering teams and stakeholders.
• Ability to balance strategic architecture with hands-on implementation.
• Experience in cloud-native, microservice environments.
• Proficiency in English (Upper-Intermediate or higher).

Responsibilities

• Design and implement core MCP platform capabilities including clients, servers, workflows, and integrations with backend services.
• Define reusable architectures, standards, and development patterns for MCP-compatible systems.
• Build shared TypeScript/Node.js libraries, SDKs, starter kits, templates, and tooling to accelerate adoption.
• Design scalable approaches for conversation state management, agent orchestration, and authentication.
• Establish guidelines for MCP, API, and service-to-service integration patterns.
• Collaborate with multiple teams to review designs, ensure consistency, and drive platform adoption.
• Create technical documentation and onboarding materials for MCP developers.
• Mentor engineers and provide technical leadership across platform initiatives.
• Contribute to long-term platform scalability, maintainability, and governance.

Skills

Principal-level leadership

Scalable architecture

MCP integration

Cloud-native microservices

LLM tool invocation patterns

Developer experience

English proficiency

TypeScript

Node.js

Tools

TypeScript

Node.js

MCP framework

SDKs and templates

Job description

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.

Job Description

• Design and implement core MCP platform capabilities, including MCP clients, servers, tool invocation workflows, and integrations with existing backend services
• Define reusable reference architectures, engineering standards, and development patterns for MCP-compatible systems
• Build shared TypeScript/Node.js libraries, SDKs, starter kits, templates, and tooling that accelerate adoption across engineering teams
• Design scalable approaches for conversation state management, agent orchestration, context handling, authentication, and versioning
• Establish architectural guidelines for selecting appropriate integration patterns, including MCP, A2A, APIs, and service-to-service communication
• Collaborate with multiple engineering teams to review technical designs, ensure consistency, and drive platform adoption
• Create technical documentation, best practices, and onboarding materials for developers working with MCP integrations
• Mentor engineers and provide technical leadership across platform and backend initiatives
• Contribute to long-term platform scalability, maintainability, and engineering governance

Qualifications

• Extensive experience in Back-End or platform engineering, including technical leadership at Principal or Staff level
• Deep understanding of scalable architecture design, interface contracts, versioning strategies, and reusable platform components
• Hands-on experience with MCP clients, servers, resources, tools, and LLM tool invocation patterns
• Experience building AI-enabled platforms or LLM-based integrations
• Knowledge of Developer Experience best practices and internal platform engineering
• Experience driving technical initiatives across multiple engineering teams and stakeholders
• Experience defining enterprise engineering standards and governance models
• Ability to balance strategic architectural thinking with hands-on implementation
• Experience working in cloud-native and microservice-based environments
• At least an Upper-Intermediate level of English

Will be a plus

• Experience with Agent-to-Agent communication and orchestration frameworks
• Familiarity with FinTech or regulated environments