Principal Software Engineer
About the role
About pubGENIUS
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.
Role Overview
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