Senior Full Stack Mern Developer

We are a U.S.based SaaS startup looking for a Senior Full Stack MERN Developer to work directly with our hands-on CTO. This is a senior role for someone who can not only ship features but also improve architecture, enforce clean code practices, and scale an MVP into a production-grade SaaS platform. **What You’ll Do**: - Take ownership of an existing MERN MVP and evolve it into a scalable, production-ready product - Refactor and improve messy or inefficient code for clarity, maintainability, and performance - Debug and resolve complex cross-layer issues quickly (MongoDB, Node.js, React, CI/CD) - Design and optimize MongoDB schemas, indexes, Atlas Search, and triggers - Build event-driven workflows with MongoDB triggers) - Integrate AI/LLM services (OpenAI, AWS Comprehend, embeddings, NLP features) into production apps - Support and improve Twilio-based messaging and webhook integrations - Contribute to new product features end-to-end (backend + frontend) **Requirements**: - Expert in MERN stack: MongoDB, Express.js, React.js, Node.js - Deep MongoDB knowledge (indexes, performance, aggregation, triggers) - Strong backend/infra skills: Node.js async/memory, AWS (EC2, S3, Lambda), CI/CD pipelines - Experience integrating AI services into production apps - Excellent English communication (mandatory) - Availability during U.S. West Coast working hours (PST/PDT) - Based in Argentina or Brazil **Benefits**: - Direct collaboration with a technical founder/CTO - Long-term role solving real production challenges (not just CRUD apps) - Remote role with U.S. time zone collaboration - Opportunity to grow into a lead role as the team expands