Senior TypeScript/Node.js Developer (Swedish Ad Platform)

Company Description

Are you passionate about building high-performance platforms that serve millions of users worldwide? We are looking for a Senior TypeScript/Node.js Developer to join our team and help transform a global AdTech product into a scalable, platform-first architecture.

At Sigma Software, we value engineering excellence, innovation, and collaboration, offering the opportunity to work on cutting-edge projects with world-class customers.

You will have the chance to work with advanced AWS serverless solutions, contribute to strategic architectural decisions, and enjoy a supportive environment with professional growth opportunities.

CUSTOMER

Our Customer is a Sweden-based AdTech company specializing in advanced self-serve advertising platforms that automate direct transactions between advertisers and major global publishers. Their technology removes traditional friction in ad sales by enabling automation, transparency, and operational efficiency at scale. Platforms are trusted by internationally recognized publishers including TripAdvisor, Bloomberg, The Washington Post, Opera, and Dow Jones, handling millions of transactions worldwide.

PROJECT

The project is a strategic architectural transformation toward a Platform-First approach. The company is transitioning from monolithic, client-specific implementations to a standardized, API-driven, multi-tenant ecosystem of reusable microservices. These services power the entire product suite, remaining independent, scalable, and decoupled from frontend or customer-specific customization.

Key Technologies: TypeScript, Node.js, AWS Lambda, API Gateway, DynamoDB, EventBridge, IaC tools (CloudFormation or Terraform), RESTful/GraphQL APIs.

Job Description

• Own and govern API design by defining and maintaining strict OpenAPI specifications before implementation begins
• Design and implement high-performance microservices using TypeScript and Node.js within a serverless AWS architecture
• Drive FinOps excellence by architecting solutions with AWS Lambda, API Gateway, DynamoDB, and EventBridge to achieve a Scale-to-Zero cost model
• Enforce logical isolation patterns across services, ensuring strict tenant data separation via JWT policies and Row-Level Security
• Maintain adherence to the Ad Context Protocol (AdCP) across all data models for consistent AdTech data language
• Develop reusable "Golden Path" templates, shared libraries, and engineering best practices
• Conduct rigorous code reviews focusing on latency (<200ms), availability (99.99%), and observability
• Translate product and commercial requirements into scalable technical specifications
• Contribute to evolving the overall platform architecture toward standardization and reusability

Qualifications

• At least 7 years of production experience as a Back-End Developer
• Strong hands-on expertise with TypeScript and Node.js
• Proven experience designing API-first microservice architectures
• Deep expertise in AWS serverless ecosystem: Lambda, API Gateway, DynamoDB, EventBridge, and IaC tools (CloudFormation or Terraform)
• Solid AdTech domain knowledge, including advertising data models and workflows
• Extensive experience designing RESTful and GraphQL APIs with versioning, backward compatibility, and documentation
• Strong understanding of multi-tenant architecture and logical data isolation patterns
• Experience building standardized platforms for multiple clients instead of custom solutions
• Strong focus on performance, reliability, and observability in distributed systems
• At least an Upper-Intermediate level of English

WILL BE A PLUS

• Experience as a Lead Back-End Developer

Additional Information

PERSONAL PROFILE

• Proactive and detail-oriented with a strong sense of ownership
• Enjoys solving complex architectural challenges
• Thrives in collaborative, cross-functional teams
• Committed to delivering high-quality solutions meeting demanding performance and reliability standards