Mainstay is looking to solve complex problems in the single family rental industry by turning complex data into clarity using AI, and is seeking a full-stack senior software engineer to help design, build, and ship complex AI-powered workflow management systems and tools.
Requirements
- 5+ years of experience building and delivering production-grade software, ideally in fast-paced, high-growth startup environment
- At least 3 years of hands-on experience developing and deploying production-ready AI features (LLM applications, fine-tuning, RAG systems, guardrails, evals, etc.)
- Strong full-stack engineering skills with a focus on backend scalability and system reliability
- Experience fine-tuning and deploying LLMs
- Deep understanding of LLM evaluation methods, including prompt testing, retrieval precision, hallucination detection, and cost/performance tradeoffs
- Experience building custom eval pipelines using techniques like model-as-a-judge or embedding similarity
- Hands-on work with agentic frameworks (e.g. LangGraph, AutoGen, CrewAI) or custom agent systems
Responsibilities
- Contribute to all phases of product development, from ideation and prototyping to implementation and iteration
- Build and evolve both frontend product experiences and backend services that power them
- Fine-tuning existing models and optimize their performance for Mainstay use cases
- Design reliable, scalable backend services to support AI-powered features in production
- Leverage AI to modernize and automate legacy workflows in the real estate industry
- Evaluate and benchmark LLM performance across latency, cost, accuracy, and hallucination rates
- Tune prompts, chain-of-thought logic, and implement retrieval strategies such as RAG and vector stores
Other
- Customer-focused mindset with a drive to build solutions that solve real problems
- Proactive and ownership-driven - comfortable navigating ambiguity and shifting priorities
- Clear, concise communicator - essential for our remote, highly collaborative team
- Mentor and support the growth of other engineers on the team
- Collaborate closely with product managers, designers, and operators to identify and solve customer pain points
