Principal Software Engineer

## About the role pubGENIUS is a React.js and Next.js development agency and ad-tech startup. We build websites and apps for clients across the US and Europe, specializing in decentralized finance (DeFi, crypto, NFT, blockchain), fintech, and healthcare, with occasional work in e-commerce and other verticals. Beyond client work, we operate our own high-revenue web product with a website, mobile app, and machine learning systems powering our ad-tech optimization engine. Performance is not a preference here, it is a core requirement. We are looking for a Principal Software Engineer, who will be the technical authority, responsible for all development, architecture decisions, and long-term technical strategy across a website, mobile app, and ML-powered ad-tech optimization systems. This is a full-time independent contractor engagement. You will work hands-on at a senior level where site speed and server performance are core success metrics. You will work directly with stakeholders to set technical direction, remove bottlenecks, and ship production-grade code. ## Engagement Details - Type: Full-time independent contractor - Hours: Full-time commitment expected - Location: Remote (US, Canada, UK, Ireland or Netherlands) - Clients: US and Europe - Rate: Competitive, based on experience ## What You'll Own - End-to-end technical ownership of a high-revenue web platform and mobile app - Architecture design and long-term technical strategy - Server-side rendering pipeline using 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 ## Requirements ### Must-Have Qualifications These are non-negotiable. Please only apply if you have strong, production-proven experience in all of the following: - Node.js with TypeScript in production - React in a server-side rendering context - MySQL including database design, query optimization, and ORM usage - BigQuery for querying and managing large-scale datasets - GCP with hands-on experience in Cloud Run, Cloud Build, Cloud SQL, and Load Balancing. GCP certification is a significant bonus. ### Nice-to-Have Experience - Ad-tech industry experience including ad serving, yield optimization, and programmatic advertising - Affiliate marketing experience, particularly with Anura and Everflow - Cloudflare including CDN configuration, caching strategies, and Workers - Fastify, especially Fastify 5 patterns - Flutter for mobile app contribution - Golang or Rust for high-performance service work - Machine learning applied to ad-tech optimization (not LLMs or agents) - Experience in DeFi, crypto, NFT, blockchain, fintech, or healthcare verticals ## Benefits - Fully remote work - Flexible hours - Paid vacation and sick days ## Application Process We do not review applications via LinkedIn DMs or email. Please apply through the designated method.