About the role

Role Overview

As a Senior Full-Stack Software Engineer at Mainstay, you’ll design, build, and ship AI-powered workflow management systems and end-to-end production-ready AI features. The role emphasizes tight customer feedback loops, high product impact, and solving complex problems across the stack.

Responsibilities

Contribute across the product lifecycle: ideation, prototyping, implementation, and iteration
Design and build reliable, scalable backend services to support AI-powered features in production
Build and evolve backend services and APIs that aggregate, enrich, and serve large real estate datasets
Develop frontend and backend experiences that make complex data intuitive, trustworthy, and actionable
Evaluate and benchmark LLM performance across latency, cost, accuracy, and hallucination rates
Own technical decisions for systems central to Mainstay’s SaaS platform, impacting investor decision-making
Partner with Product, Design, Data Science, and Data Engineering to deliver durable solutions
Improve reliability, performance, and maintainability as the platform scales
Modernize and automate legacy real estate workflows by replacing manual analysis with software-driven insights
Mentor engineers via code reviews, technical guidance, and shared team standards

Requirements

5+ years building and shipping production-grade software in fast-paced, early-stage environments
Hands-on experience developing and deploying production-ready AI features
Strong AI-first thinking and software engineering best practices
Backend-first full-stack skills, with deep experience designing and operating scalable backend systems (ideally Python)
Solid frontend experience with React (or similar modern frameworks)
Experience with data-heavy analytics/workflow-oriented systems
Strong technical judgment balancing speed, correctness, and maintainability
Clear communication skills for a remote, collaborative team
Proactive, ownership-driven approach to ambiguous problems

Nice-to-haves / Fit Signals

Interest in high-leverage systems that affect how institutional investors deploy capital
Enjoy owning complex problems from problem definition through production impact
Comfortable influencing technical direction and raising engineering quality

About Mainstay

Mainstay is an AI-native market intelligence platform focused on buying, managing, and selling homes in the single-family rental industry. It turns complex real estate and operational data into clear, actionable insights to help the industry move forward with confidence. Founded in 2024 as an independent company within Opendoor, Mainstay recently raised a Series A round led by Khosla Ventures.