Principal Software Engineer (React Node) - Remote -EU or USA

Principal Software Engineer at pubGENIUS, a React.js and Next.js development agency and ad-tech startup. You are the technical authority responsible for all development, architecture decisions, and long-term technical strategy for website, mobile app, and ML-powered ad-tech optimization systems.

You have full technical ownership of a high-revenue web platform and mobile app, including architecture design and long-term technical strategy. Key responsibilities include:

• Server-side rendering pipeline with Node.js, Fastify 5, and React 19
• Data layer across MySQL and BigQuery
• GCP infrastructure including Cloud Run, Cloud Build, and Global Load Balancer
• Ad-tech integrations including Google Ad Manager, GTM, GTag, and GPT.js
• Performance optimization at scale, where every millisecond counts
• ML pipeline maintenance and optimization for ad-tech performance

You work hands-on at a senior level where site speed and server performance are core success metrics, working directly with stakeholders to set technical direction, remove bottlenecks, and ship production-grade code.