Senior Software Engineer, Backend (AI)

About the role

We are seeking a Senior Backend Engineer to join our newly formed AI R&D pod. This role focuses on building the future of AI-native product experiences at Posh, with a strong emphasis on systems architecture and AI implementation.

Responsibilities

• Design, build, and maintain scalable backend services and APIs for AI-powered features, writing primary production code in Python.
• Move beyond standard RAG to design and implement complex, hierarchical Multi-Agent Systems that can perform sophisticated, multi-step tasks.
• Build robust frameworks to evaluate the quality of AI systems and manage fine-tuning pipelines to continuously improve model performance.
• Define, deploy, and manage our AI infrastructure using Terraform. Responsible for scaling our container-based serverless solutions while ensuring reliability and performance.
• Deeply analyze the tradeoffs between model performance, latency, and cost to make pragmatic, business-aware technical decisions when using managed AI services.
• Collaborate with our core engineering teams by occasionally working in TypeScript (Node.js) to integrate AI features into our main application.

Requirements

• 3–6+ years of backend or full-stack engineering experience, with a proven track record of shipping high-quality, scalable systems in fast-paced environments.
• Deep expertise in Python and its ecosystem for web services and data processing.
• Strong experience with Infrastructure as Code (Terraform), a major cloud platform (e.g., GCP, AWS, Azure), and deploying containerized applications.

Qualifications

• A passion for shaping 0→1 products in a lean, fast-paced R&D environment where you'll help define new playbooks for AI-native experiences.
• Bonus points for pragmatic AI/ML exposure: familiarity with managed AI services (e.g., Vertex AI, AWS Bedrock), working with LLMs, or building advanced AI systems.
• Experience with model evaluation frameworks (e.g., RAGAs, LangSmith, DeepEval) or fine-tuning.
• The ability to think about tradeoffs between cost, latency, and performance.
• Experience with open-source agentic frameworks (e.g., LangGraph, CrewAI, Strands, etc).
• Experience with MLOps, data engineering, or a background in consumer, marketplace, or event-driven platforms.

Benefits

This is a 5 day a week commitment at our NYC office in SoHo.

Pay

$200K - $225K

Schedule

5 day a week commitment at our NYC office in SoHo.