Senior Node.js/TypeScript Backend Architect

Solid Company; Kraków; Hybrid; PLN 180,000 - 280,000; Full time

Job summary

Solid Company Kraków is seeking a skilled backend engineer to design, develop, and maintain REST APIs and services using Node.js, Express, TypeScript, and ES6+. You will work on middleware, data handling, and scalable architectures in a distributed, international team.

You will write unit and integration tests, optimize performance, and implement observability and CI/CD pipelines with Azure DevOps or GitHub Actions.

Qualifications

• Strong commercial experience with JavaScript (ES6+) and TypeScript.
• Solid knowledge of TypeScript fundamentals, including interfaces, generics, type inference, and type safety.
• Experience with TypeScript configuration (tsconfig.json) and integration with build tools.
• Hands-on experience developing backend applications and REST APIs using Node.js and Express.
• Good understanding of the Node.js event loop, asynchronous execution, batch processing, and database transactions.
• Experience with unit and integration testing using Jest, Vitest, or similar frameworks, including TDD practices.
• Strong debugging and troubleshooting skills, including performance analysis and regression investigation.
• Experience managing dependencies within the NPM ecosystem, including package versioning and security vulnerability remediation.
• Practical experience with Azure DevOps or GitHub Actions and CI/CD pipelines.
• Experience with AI-assisted development and agentic coding, including Claude Code or GitHub Copilot, MCP, skill design, and context engineering.
• Experience designing observability and corrective tooling for production systems.
• Strong understanding of software engineering best practices and maintainable code design.
• Fluent in English and experience working in international, distributed teams.

Responsibilities

• Design, develop, and maintain backend applications and REST APIs using Node.js, Express, JavaScript, and TypeScript.
• Build and maintain middleware layers and service integrations.
• Write clean, maintainable, and well-tested code following modern software development practices.
• Develop and maintain unit and integration tests using Jest, Vitest, or similar frameworks, applying TDD principles.
• Analyze and troubleshoot runtime errors, performance issues, and application regressions.
• Work with asynchronous processing, batch operations, and database transactions.
• Identify and resolve security vulnerabilities in application code and dependencies.
• Configure, maintain, and troubleshoot CI/CD pipelines using Azure DevOps or GitHub Actions.
• Design and implement observability, monitoring, and corrective tools for operations and support teams.
• Leverage AI-assisted and agentic coding tools, including Claude Code, GitHub Copilot, and MCP.
• Collaborate with international development and operations teams.

Skills

JavaScript/TypeScript

TypeScript fundamentals

Unit & integration testing

English fluency

Tools

Node.js

Express

Azure DevOps

GitHub Actions

Job description

Solid Company Kraków is seeking a skilled backend engineer to design, develop, and maintain REST APIs and services using Node.js, Express, TypeScript, and ES6+. You will work on middleware, data handling, and scalable architectures in a distributed, international team.

You will write unit and integration tests, optimize performance, and implement observability and CI/CD pipelines with Azure DevOps or GitHub Actions.