Sr. Machine Learning Engineer

AppFolio is hiring a Senior Machine Learning Engineer to design and ship production voice and conversational AI agents within the Realm-X AI-native platform.

Responsibilities

• Architect and ship voice and text agent pipelines for real-time, multi-turn customer interactions
• Make principled trade-offs between reasoning depth and latency across frontier LLMs, smaller models, and routing strategies
• Lead a small pod of ML and platform engineers; improve agent evaluation, observability, and incident response
• Partner with Product and Voice channel teams to define KPIs, eval harnesses, and acceptance criteria for agent quality
• Drive selective SLM fine-tuning and inference optimization to reduce voice latency and cost
• Turn cutting-edge agent and voice research into reliable, low-latency, multi-channel experiences at scale across AppFolio’s customer base

Requirements

• 5+ years building and scaling web-based applications, ideally in a SaaS environment
• Shipped production AI agents serving real users in voice and/or text channels
• Systems mindset: think in pipelines and systems, not only models
• Sound engineering judgment
• Humility, collaboration, and low-ego approach; ability to elevate others
• Values work-life balance as a basis for sustained performance
• Deep, shipped experience with LangChain, LangGraph, LangSmith, and LangChain Deep Agents (or equivalent agent frameworks)
• Hands-on with Voice-to-Voice models and traditional TTS/STT pipelines, including trade-offs between end-to-end voice models and modular STT + LLM + TTS architectures
• Strong understanding of LLM reasoning behavior, tool use, structured output, and reasoning-vs-latency trade-offs across providers
• Production experience with Twilio (or comparable telephony) and AWS
• Expert Python, async programming, and WebSockets for real-time bidirectional streaming
• Foundation in deep learning, model evaluation, and inference optimization; deploy with Docker on AWS
• Experience leading a small team, mentoring engineers, and partnering credibly with Product and Design

Technologies

• Python
• Async programming
• WebSockets
• LangChain
• LangGraph
• LangSmith
• LangChain Deep Agents
• Voice-to-Voice models
• TTS
• STT
• LLM
• Small Language Models (SLM)
• Twilio
• AWS
• Docker
• Real-time, bidirectional streaming

Nice to Have

• Bachelor’s, Master’s, or Ph.D. in Computer Science or a related technical discipline
• Experience fine-tuning Small Language Models for domain-specific voice applications
• Familiarity with RAG over structured business data and tool-using agents over API surfaces
• Experience in regulated or customer-facing industries with strict reliability requirements
• Publicly verifiable work on GitHub, open-source agent frameworks, or community competitions

Location

• Atlanta, GA (onsite)
• Find out more about locations by visiting the company site
• All late-stage candidates complete an in-person meeting with an AppFolian as part of the hiring process

Compensation & Benefits

• Base pay: $167,200 - $229,900 per year
• Actual compensation depends on factors including skills, education, experience, and internal equity
• Regular full-time employees are eligible for benefits (details available via the provided link)