Principal Software Engineer (React + Node) - Remote -EU or USA
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 or EOR
- Hours: Full-time commitment expected
- Location: Remote
- 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 application link
- We do not work with staffing agencies or third-party recruiters. Direct applicants only
pubGENIUS is an Equal Opportunity Employer; employment with pubGENIUS is governed on the basis of merit, competence, and qualifications and will not be influenced in any manner by race, age, colour, gender, religion, national origin/ethnicity, veteran status, sexual orientation, marital status, gender identity, mental or physical disability, or any other legally protected status. Apply To This Job