Strong Middle / Senior Full Stack Developer (TypeScript / React)

Sigma Software; Województwo mazowieckie; On-site; PLN 180,000 - 300,000; Full time

Job summary

Sigma Software is seeking a Strong Middle / Senior Full Stack Developer to join a product-focused team building a large-scale AdTech platform. You will work across backend with NestJS and frontend with ReactJS, leveraging TypeScript and AWS to deliver enterprise-grade solutions.

The role emphasizes ownership, architecture input, and collaboration with architects, QA, and PMs on high-load campaigns and media workflows.

Qualifications

• 4-5+ years of commercial software development with JavaScript/TypeScript (backend focus)
• Strong backend experience with NestJS
• Solid frontend experience with ReactJS
• Hands-on experience with AWS cloud services
• Experience with enterprise/high-load applications
• Good communication and collaboration skills
• Upper-intermediate or higher English level

Responsibilities

• Design, develop, and maintain scalable Full Stack apps using JavaScript, TypeScript, NestJS, and React
• Implement complex business logic related to digital advertising campaign management
• Participate in architecture discussions, technical decisions, and solution design activities
• Collaborate with developers, architects, QA engineers, and project managers
• Improve application performance, scalability, reliability, and maintainability
• Develop clean, maintainable, and well-tested code following software engineering best practices
• Identify technical challenges proactively and drive solutions independently
• Contribute to continuous improvements in development processes and technical standards

Skills

JavaScript / TypeScript

Problem solving

Communication

Independent ownership

Teamwork

English proficiency

Tools

NestJS

ReactJS

AWS

Job description

Join a product-focused engineering team developing a large-scale AdTech platform used for managing and optimizing digital advertising campaigns across multiple channels.

We are looking for a Strong Middle /Senior Full Stack Developer with strong TypeScript expertise, solidBack-end development experience with NestJS, and hands-on Front-end experience with ReactJS. In this role, you will work on enterprise-level solutions with complex business workflows, media processing pipelines, and deep integrations with advertising ecosystems.

We at Sigma Software offer the opportunity to work on technically challenging products, collaborate with experienced engineering teams, and contribute to scalable solutions used in a dynamic digital advertising domain.

CUSTOMER

Our Customer is an international company operating in the digital advertising and AdTech industry. The company develops enterprise-grade technology solutions that help advertisers and media organizations manage, optimize, and scale digital advertising campaigns. Their products support high-load advertising operations, complex workflows, and media-related processes across modern advertising ecosystems.

PROJECT

The project is a large-scale advertising campaign management platform covering the full lifecycle of digital campaigns. The solution includes campaign creation and configuration, line-item management, creatives handling, forecasting, SLA tracking, and integrations with external advertising and media services. The platform also supports advanced media workflows such as video transcoding and image validation.

The engineering team is focused on building scalable and reliable enterprise solutions with sophisticated business logic and multiple integrations while continuously improving performance, maintainability, and operational efficiency.

• Design, develop, and maintain scalable Full Stack applications using JavaScript, TypeScript, NestJS, and React
• Implement and support complex business logic related to digital advertising campaign management
• Participate in technical discussions, architecture decisions, and solution design activities
• Collaborate closely with developers, Architects, QA engineers, and Project Managers
• Improve application performance, scalability, reliability, and maintainability
• Develop clean, maintainable, and well-tested code following software engineering best practices
• Identify technical challenges proactively and drive solutions independently
• Contribute to continuous improvements in development processes and technical standards

• 4-5+ years of commercial software development experience with JavaScript and TypeScript, with a primary focus on back-end development
• Strong Back-end development experience with NestJS
• Solid Front-end development experience with ReactJS
• Hands-on experience with AWS cloud services
• Good understanding of scalable system architecture and software engineering best practices
• Experience working with enterprise-level or high-load applications
• Strong problem-solving and analytical skills
• Ability to work independently and take ownership of technical solutions
• Good communication and collaboration skills
• Upper-Intermediate or higher English level

WILL BE A PLUS

• AI-native development experience
• Familiarity with AI-powered development tools such as Claude and Codex
• Experience with Jenkins
• Experience with Terraform
• Experience working with complex or enterprise platforms

PERSONAL PROFILE

• Proactive and self-driven mindset
• Strong ownership attitude
• Team-oriented and collaborative approach
• Ability to work effectively in a fast-paced engineering environment
• Strong attention to code quality and technical excellence