Senior Full-Stack Software Engineer, AI

ABOUT MAINSTAY Mainstay is the leading market intelligence platform purpose built for buying, managing, and selling homes in the single family rental industry. As an AI native company, we turn complex data into clarity that helps the industry move forward with confidence. Founded within Opendoor, Mainstay launched as an independent company in 2024 and recently raised a Series A round led by Khosla Ventures. Ready to shape the future of real estate with AI? Join Mainstay and help us redefine what’s possible in the single family rental space. If you thrive on solving complex problems and want to make a tangible impact in a fast-growing industry, we’d love to hear from you - apply now and let’s move the industry forward, together! ABOUT THE ROLE What you should expect as a full-stack senior software engineer - maximum agency, tight feedback loops with customers, and no shortage of product challenges that directly translate to business value! You’ll have the opportunity to design, build, and ship complex AI-powered workflow management systems and tools that enable our operations team to execute at scale. We’re looking for someone who can use AI to efficiently ship features across the stack and ship reliable, production ready AI features end to end - from retrieval pipelines and guardrails to backend systems and user facing product experiences. Our products are built with Python, Typescript, and React on AWS. In this role you will - Contribute to all phases of product development, from ideation and prototyping to implementation and iteration - Design reliable, scalable backend services to support AI-powered features in production - Build and evolve scalable backend services and APIs that aggregate, enrich, and serve large, complex real estate datasets - Develop and refine frontend and backend product experiences that make sophisticated data intuitive, trustworthy, and actionable - Evaluate and benchmark LLM performance across latency, cost, accuracy, and hallucination rates - Own technical decisions for systems that sit at the center of Mainstay’s SaaS platform and directly influence investor decision-making - Partner closely with product managers, designers, data science, and data engineering to translate business needs into durable technical solutions - Improve system reliability, performance, and maintainability as the platform scales - Modernize and automate legacy real estate workflows by replacing manual analysis with software-driven insights - Mentor other engineers through code reviews, technical guidance, and shared ownership of team standards What we’re looking for - 5+ years of experience building and shipping production-grade software in fast-paced and early-stage start up - Proven, hands-on experience developing and deploying production-ready AI features - Highly proficient with AI-first thinking and software development best practices - Strong full-stack engineering skills with a backend-first…