Senior AI/ML Engineer — Matching & Conversational Pipelines

Praxis, Inc.; San Francisco (CA); On-site; USD 180,000 - 240,000; Full time

Job summary

Praxis, Inc. invites a technical founder to drive the ML/AI backbone for Known, a dating platform that blends psychology, data, and human-like conversation. You will design and ship matching systems, adaptive recommendations, and natural voice interactions.

You will partner with the founding team to shape data and ML foundations and user-facing experiences, owning research, prototyping, and production deployment from day one.

Qualifications

• 3+ years in applied ML or data science engineering roles.
• Strong proficiency in Python and modern ML frameworks (PyTorch, TensorFlow, JAX, Hugging Face).
• Experience with LLMs, embeddings, and agentic workflows.
• Understanding of A/B testing and human-in-the-loop system design for model evaluation in production.
• Familiarity with ANN search systems and modern MLOps tools is a plus.
• Reinforcement learning or preference modeling experience is a strong plus.
• You care about building safe, fair, and human-centered AI experiences.

Responsibilities

• Design and implement multi-stage matching systems (embedding-based retrieval + LLM re-ranking).
• Develop and maintain ML pipelines for data ingestion, feature generation, model training, evaluation, and inference.
• Prototype and productionize agentic workflows for natural-language and voice interactions.
• Deploy and monitor ML models in production with guardrails for performance, fairness, and safety.
• Run offline & online experiments (A/B and multivariate) to measure engagement, match success rate, and conversation quality.
• Collaborate cross-functionally with platform engineers and product designers to integrate AI into the Known user experience.

Skills

Python

ML frameworks

LLMs

Embeddings

A/B testing

MLOps

ANN search

Agentic workflows

Reinforcement learning

Tools

PyTorch

TensorFlow

JAX

Hugging Face

Job description

Praxis, Inc. invites a technical founder to drive the ML/AI backbone for Known, a dating platform that blends psychology, data, and human-like conversation. You will design and ship matching systems, adaptive recommendations, and natural voice interactions.

You will partner with the founding team to shape data and ML foundations and user-facing experiences, owning research, prototyping, and production deployment from day one.