About the role

Role Overview

Principal Software Engineer (Node.js, SQL)

You will act as a key technical authority overseeing development, architecture decisions, and long-term technical strategy across a web platform, mobile applications, and machine-learning-powered ad-tech systems. The role is hands-on at a senior/principal level, with a strong emphasis on performance: site speed and server responsiveness.

Responsibilities

Own end-to-end technical development and architecture for a high-revenue web platform and mobile app
Design and implement scalable, efficient system architecture aligned with long-term strategy
Build and optimize server-side rendering pipelines using Node.js, Fastify 5, and React 19
Develop and optimize data layers across MySQL and BigQuery for large-scale data management
Configure and maintain GCP infrastructure (Cloud Run, Cloud Build, Cloud SQL, Load Balancer)
Integrate and maintain ad-tech systems (Google Ad Manager, GTM, GPT.js)
Lead performance optimization initiatives to improve load times and server responsiveness
Maintain and enhance machine learning pipelines supporting ad-tech performance and accuracy
Collaborate with stakeholders to set technical direction, remove bottlenecks, and ensure production-grade delivery

Qualifications

Proven production experience with Node.js and TypeScript
Extensive experience with React, especially server-side rendering contexts
Strong MySQL knowledge (database design, query optimization, ORM usage)
Hands-on experience with BigQuery for large-scale datasets
Proficiency with Google Cloud Platform services: Cloud Run, Cloud Build, Cloud SQL, and Load Balancer
Experience with ad-tech integrations including Google Ad Manager, GTM, GTag, and GPT.js
Demonstrated ability to optimize performance at scale (millisecond-level improvements)
Knowledge of machine learning pipelines and ongoing maintenance for ad-tech performance

Nice-to-Haves

Deep experience in high-revenue, performance-critical digital products operating at scale

Contract & Work Setup

Full-time independent contractor
Remote from the US, Canada, UK, Ireland, or the Netherlands
Flexible working hours across time zones

About Sundayy

pubGENIUS is a development agency and startup focused on ad-tech solutions and blockchain-related projects. It builds high-performance websites, applications, and machine-learning-powered systems for clients across the US and Europe, working with industries such as DeFi, fintech, crypto, NFTs, and healthcare.

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