Senior Full Stack Developer, Node React

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.

We are prioritizing candidates based in Argentina or Brazil to align with U.S. West Coast (Los Angeles) working hours.

• 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