Mainstay

Senior Software Engineer, Applied AI

Mainstay

full-time

Posted on:

Origin:  • 🇺🇸 United States

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Salary

💰 $158,100 - $232,500 per year

Job Level

Senior

Tech Stack

AWSPythonReactTypeScript

About the role

  • Mainstay: market intelligence platform for buying, managing, and selling homes in the single-family rental industry, aggregating and standardizing data from 50+ sources
  • Role: Senior full-stack software engineer focused on Applied AI, designing, building, and shipping AI-powered workflow management systems and tools
  • Responsibilities include fine-tuning and optimizing models, designing retrieval pipelines and guardrails, building scalable backend services, and creating user-facing product experiences
  • Work closely with product managers, designers, and operators to bring AI features from idea to launch while balancing innovation with stability
  • Monitor LLM performance, safety, and cost in production; tune prompts and implement retrieval strategies such as RAG and vector stores; mentor other engineers

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
  • Clear, concise communicator
  • Proactive and ownership-driven; comfortable navigating ambiguity and shifting priorities
  • Customer-focused mindset with a drive to build solutions that solve real problems
  • Experience with AI/ML tools or APIs; bonus if you’ve worked with Python-based RAG, voice agents, or AI task automation
  • Bonus: Experience working with retrieval-augmented generation (RAG) pipelines
  • Bonus: Exposure to building or integrating voice agents
  • Bonus: Familiarity with task automation powered by AI
  • Bonus: Strong Python background with applied AI or ML workflows