Sr. Machine Learning Engineer

AppFolio is seeking a Senior Machine Learning Engineer to design and ship voice and conversational AI agents within Realm-X. The role focuses on building production agent pipelines that balance LLM reasoning quality with low-latency, real-time streaming across multi-channel customer experiences.

Responsibilities

• Architect and deliver voice and text agent pipelines that support real-time, multi-turn customer interactions.
• Make principled trade-offs between reasoning depth and latency when using frontier LLMs, smaller models, and routing strategies.
• Lead a small pod of ML and platform engineers, improving agent evaluation, observability, and incident response practices.
• Collaborate with Product and Voice channel teams to define KPIs, evaluation harnesses, and acceptance criteria for agent quality.
• Drive selective Small Language Model (SLM) fine-tuning and optimize inference to meet voice latency and cost targets.

Requirements

• Deep, production experience with LangChain, LangGraph, LangSmith, and LangChain Deep Agents (or equivalent agent frameworks).
• Hands-on experience with Voice-to-Voice models as well as traditional TTS / STT pipelines, including understanding 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-versus-latency trade-offs across model providers.
• Production experience with Twilio (or comparable telephony) and AWS.
• Expertise in Python, async programming, and WebSockets for real-time, bidirectional streaming.
• Solid foundation in deep learning, model evaluation, and inference optimization, with the ability to deploy using Docker on AWS.
• Proven ability to lead a small team, mentor engineers, and partner credibly with Product and Design.
• Experience shipping production AI agents serving real users in voice and/or text channels.
• Systems-oriented thinking, with a focus on pipelines rather than only model development.
• Ability to move quickly, deliver impact, and apply sound engineering judgment.
• Collaborative, low-ego leadership and a willingness to elevate others.
• Commitment to work-life balance as a foundation for sustained high performance.

Technologies

• LangChain, LangGraph, LangSmith, LangChain Deep Agents
• Voice-to-Voice models, TTS, STT
• Twilio, AWS
• Python, async programming, WebSockets
• Docker
• LLM, Small Language Model (SLM), RAG

Nice to Have

• 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 environments with strict reliability requirements.
• Publicly verifiable work on GitHub, in open-source agent frameworks, or in community competitions.

Benefits

• Regular full-time employees are eligible for benefits
• #LI-KB1

Compensation & Total Rewards

The compensation that AppFolio reasonably expects to pay for this role is $167,200 - $209,000 base pay on a yearly basis.

The actual compensation for this role will be determined by factors including skills, education, experience, and internal equity. Compensation is one aspect of a comprehensive Total Rewards package, and the range listed does not include additional benefits or any discretionary bonuses based on role and/or employment type.

Regular full-time employees are eligible for benefits; see details on the company site.

Location

Atlanta, GA (onsite). Find out more about locations by visiting the company site.