Principal Software Engineer

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 Defi, fintech, healthcare, and education 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 to be the technical authority, responsible for all development, architecture decisions, and long-term technical strategy across our website, mobile app, and ML-powered ad-tech optimization systems. This is a hands-on senior role 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

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

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 fintech,

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.