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. 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 seniority level mid‑senior level employment type contract job function it services and it consulting j-18808-ljbffr