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 orientation

Deep experience designing, building, and operating scalable backend systems, ideally in Python

Solid frontend experience with React or similar modern frameworks

Experience working with data-heavy, analytics-driven, or workflow-oriented systems

Strong technical judgment and the ability to balance speed, correctness, and long-term maintainability

Clear, thoughtful communication skills for a remote, highly collaborative team

A proactive, ownership-driven approach to ambiguous problems

This role is a great fit if

You want to work on high-leverage systems that directly shape how institutional investors deploy capital

You enjoy owning complex technical problems from problem definition through production impact

You like working at the intersection of data, product, and business decision-making

You’re comfortable influencing technical direction and raising the bar for engineering quality

You thrive in environments with autonomy, responsibility, and evolving priorities with strong ownership

Not a great fit if

You lack strong backend experience or are uncomfortable owning production systems in Python

You prefer narrowly scoped tasks over end-to-end ownership

You avoid frontend or product-facing work You struggle with ambiguity, changing requirements, or close cross-functional collaboration

You prefer highly rigid processes and minimal iteration

Tools we use

Languages: Python, TypeScript

Backend: FastAPI, Django

Frontend: React, Next.js

Data: Airflow, dbt, Snowflake, PostgreSQL

Infra: AWS, Terraform

Tooling: GitHub

Mainstay Built on Trust

At Mainstay, trust is at the core of everything we do. We build trust with everyone -- from candidates to employees to partners. We believe in fairness and openness throughout our hiring process, evaluating candidates based on qualifications without regard to race, color, religion, national origin, age, gender, marital status, disability, veteran status, sexual orientation, gender identity, or any other protected status. Our privacy practices describe how we handle applicant information, you can find the policy details for California residents here .

We are committed to providing reasonable accommodations throughout our recruitment processes for candidates with disabilities, pregnancy, religious beliefs, or other reasons protected by applicable laws. If you require assistance or a reasonable accommodation, please contact us at [email protected]