Senior Full-Stack Software Engineer
Mainstay · United States
- Hybrid
- Full-time
- $150,000 / year
- United States
Job highlights
- Build AI-powered real estate intelligence platform.
- Design and ship full-stack features.
- Work with Python, Typescript, React, AWS.
- Evaluate LLM performance and ensure reliability.
- Mentor engineers and own technical decisions.
About the role
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 mainstay-recruiting@opendoor.com
Key skills/competency
- Full-Stack Development
- AI/ML Feature Development
- Python Backend Development
- React Frontend Development
- AWS Infrastructure
- System Design & Architecture
- Data Engineering
- Workflow Management Systems
- LLM Performance Evaluation
- Technical Leadership & Mentorship
Skills & topics
- Senior Full-Stack Software Engineer
- Python
- React
- AWS
- AI
- Machine Learning
- Software Development
- Full Stack
- Backend Development
- Frontend Development
- System Design
- Real Estate Tech
- Startup
- TypeScript
- FastAPI
- Django
- Next.js
- LLM
- Workflow Management
How to get hired
- Tailor your resume: Highlight 5+ years of production software, AI features, and Python/React experience.
- Showcase AI proficiency: Emphasize AI-first thinking and experience shipping end-to-end AI features.
- Demonstrate full-stack skills: Detail your backend-first approach and experience with scalable systems.
- Align with culture: Express your interest in autonomy, ownership, and collaborative environments.
- Prepare for technical interviews: Be ready to discuss system design, AI implementation, and Python/React challenges.
Technical preparation
Behavioral questions
Frequently asked questions
- What is Mainstay's company culture like for a Senior Full-Stack Software Engineer?
- Mainstay fosters a culture of high agency, tight feedback loops, and direct customer impact. As a Senior Full-Stack Software Engineer, you'll experience autonomy, responsibility, and evolving priorities within a collaborative, remote-first team that values ownership and quality.
- What are the primary technical challenges for a Senior Full-Stack Software Engineer at Mainstay?
- The primary technical challenges involve designing, building, and shipping complex AI-powered workflow management systems. This includes developing end-to-end AI features from retrieval pipelines to backend services and user-facing experiences, while also evaluating LLM performance and ensuring system scalability and reliability on AWS.
- What is the expected experience level for a Senior Full-Stack Software Engineer at Mainstay?
- Mainstay is looking for candidates with at least 5 years of experience building and shipping production-grade software, particularly in fast-paced, early-stage startups. Proven hands-on experience with developing and deploying production-ready AI features is crucial, along with strong full-stack skills and a backend-first orientation.
- How does Mainstay utilize AI in its platform and what is the role of the Senior Full-Stack Software Engineer in this?
- Mainstay is an AI-native company that uses AI to provide market intelligence for the single-family rental industry. As a Senior Full-Stack Software Engineer, you will be instrumental in building and shipping AI-powered workflow systems, developing end-to-end AI features, and evaluating LLM performance to enhance the platform's capabilities.
- What specific technologies will I be working with as a Senior Full-Stack Software Engineer at Mainstay?
- You will work with a modern tech stack including Python and TypeScript for languages, FastAPI and Django for backend, React and Next.js for frontend, and AWS for infrastructure. Data tools like Airflow, dbt, Snowflake, and PostgreSQL are also part of the ecosystem.
- What does 'AI-first thinking' mean for a Senior Full-Stack Software Engineer at Mainstay?
- AI-first thinking means approaching software development with AI capabilities at the forefront. For this role, it involves designing systems that leverage AI for efficiency, developing AI features end-to-end, and considering AI-specific challenges like LLM performance, latency, and accuracy from the outset.