Strong Mid/Senior Full Stack Developer

Company 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, solid Back-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. Job Description Design, develop, and maintain scalable Full Stack applications using JavaScript, TypeScript, NestJS, and ReactImplement and support complex business logic related to digital advertising campaign managementParticipate in technical discussions, architecture decisions, and solution design activitiesCollaborate closely with developers, Architects, QA engineers, and Project ManagersImprove application performance, scalability, reliability, and maintainabilityDevelop clean, maintainable, and well-tested code following software engineering best practicesIdentify technical challenges proactively and drive solutions independentlyContribute to continuous improvements in development processes and technical standards Qualifications 4-5+ years of commercial software development experience with JavaScript and TypeScript, with a primary focus on back-end developmentStrong Back-end development experience with NestJSSolid Front-end development experience with ReactJSHands-on experience with AWS cloud servicesGood understanding of scalable system architecture and software engineering best practicesExperience working with enterprise-level or high-load applicationsStrong problem-solving and analytical skillsAbility to work independently and take ownership of technical solutionsGood communication and collaboration skillsUpper-Intermediate or higher English level WILL BE A PLUS AI-native development experienceFamiliarity with AI-powered development tools such as Claude and CodexExperience with JenkinsExperience with TerraformExperience working with complex or enterprise platforms Additional Information PERSONAL PROFILE Proactive and self-driven mindsetStrong ownership attitudeTeam-oriented and collaborative approachAbility to work effectively in a fast-paced engineering environmentStrong attention to code quality and technical excellence