React Next Js Developer Jobs in New Rochelle, NY

As a Full Stack Software Engineer at InstaLILY, you'll own meaningful pieces of our AI agent platform: the core systems that let autonomous agents reason, act, and integrate into our enterprise customers' workflows. You'll work alongside the Lead Software Engineer and a team drawn from top-tier programs to design, build, and ship the platform features that show up in production at our customers. You'll work across the stack, from backend services and agent infrastructure to APIs and the web interfaces our customers actually touch.

This role is deeply client-facing. You won't be coding in a vacuum and handing off to a customer success team. You'll be in the room with our customers from the start. You'll sit in working sessions with enterprise stakeholders, run technical discovery, translate messy real-world workflows into shipped features, and embed with customer teams during rollouts. The best engineers here are the ones who can switch between writing production code in the morning and walking a Fortune 500 VP through a system architecture in the afternoon. You need to code at a high bar, make architectural decisions you can defend, and explain them clearly to people who don't speak engineer.

• Own end-to-end design and delivery of features across the full stack: backend services, agent infrastructure, APIs, and customer-facing web UIs
• Build, ship, and operate LLM-powered systems: agents, RAG pipelines, tool-use frameworks, evaluation harnesses, and the supporting infrastructure that makes them reliable in production
• Lead technical discovery with new enterprise customers; sit with their teams, map their workflows, and translate what you hear into shipped product
• Embed with customer teams during deployments and rollouts; be the engineering presence in the room, not the one waiting for a Jira ticket
• Present architecture and technical tradeoffs to non-technical executives at our customers, and defend them under pressure
• Partner with the Growth team to turn customer feedback into roadmap; iterate on what's actually being used vs. what we thought would be useful
• Raise quality and reliability across the codebase through comprehensive testing, code review, and CI/CD practices
• Mentor junior engineers: pair on hard problems, review their code thoughtfully, and help them level up
• Contribute to architectural discussions and technical reviews; help shape how we build as we scale
• Stay current on AI/ML and software engineering trends, and bring back what's worth adopting

• Bachelor's or Master's in CS, engineering, math, physics, or related: demonstrated ability matters more than credential
• 3-5 years of experience as a software engineer, with a track record of shipping production systems across the full stack
• Strong fluency on the backend (Python, TypeScript, or similar) and the frontend (React, Next.js, modern TypeScript)
• Solid grasp of system design fundamentals (API design, data modeling, async patterns, caching, queues) and frontend architecture (component design, state management, performance)
• Production experience with cloud infrastructure (AWS, GCP, or Azure) and CI/CD pipelines
• AI-serious: you've built and shipped something real with LLMs (a production RAG system, an agent in customer hands, a non-trivial integration), and you have opinions on what works and what doesn't
• Comfortable in front of customers: you can run a technical discovery session, defend an architectural decision to a non-technical exec, and translate vague enterprise requirements into something concrete
• Strong written and verbal communication: you can write a clear design doc, send a clean customer-facing update, and present to a room without disappearing into jargon

• Experience mentoring junior engineers, leading technical reviews, or owning a meaningful surface of a codebase
• Prior experience in a forward-deployed, solutions engineering, or client-embedded role at a B2B software company

We're a TypeScript + Python shop. You'll work with these every day:

• Frontend: TypeScript, React, Next.js (deployed on Vercel)
• Backend: Python, FastAPI, SQLAlchemy
• Database: PostgreSQL with Alembic for migrations
• Infrastructure: GCP, Docker
• Workflow orchestration: Temporal
• Lots of third-party integrations into our enterprise customers' systems

Required: TypeScript, React/Next.js, Python, FastAPI, SQLAlchemy, PostgreSQL

Nice to have: GCP, Vercel, Temporal, Alembic, Docker, prior experience with third-party / enterprise system integrations

You don't need to have used every tool on our stack; strong engineers ramp quickly. But you should be genuinely fluent in the required core: TypeScript on the frontend and Python on the backend, with real production experience shipping features end-to-end.

• Proven product: Customers are live; this isn't a bet on an unproven thesis
• AI-native: In how we build, how we work, and what we sell
• Stage: Early enough to shape how the company builds and scales
• Customer access: Real seats at the table with enterprise customers; you'll learn how the largest companies in the world actually buy, deploy, and use software
• Global: Based in New York with offices in SF and London
• Culture: Sharp, low-ego team that keeps raising the bar
• Growth: The learning curve is steep

• Salary Range: $150,000-$190,000 per year, commensurate with experience
• Equity: Stock options awards, and refreshers for top performers
• Benefits: Medical, Dental, Vision, 401K, in-office Lunch reimbursement, Wellbeing Stipend, Generous Parental leave, PTO and 10 US Federal Holidays, and more!

Join InstaLILY and build autonomous agents that matter. If you want a role where you own real surfaces of an AI platform, where your code ships into real enterprise systems, and where you're in the room with the customers using them, we want to hear from you.