AI / ML Engineer - Known

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

About the Role

You’ll be the technical founder driving the machine learning and AI backbone behind Known — an intelligent, compatibility-driven dating platform that blends psychology, data, and human-like conversation. You’ll design and ship the systems that make Known feel magical: personalized matching algorithms, adaptive recommendation loops, and natural voice/LLM-based interactions that help users connect meaningfully.

You’ll work closely with the founding team (product, platform, and design) to shape both the data and ML foundations and the user-facing experiences that differentiate Known. This is a hands-on role with ownership across research, prototyping, and production deployment.

Responsibilities

• Design and implement multi-stage matching systems (embedding-based retrieval + LLM re-ranking) for compatibility scoring, search, and personalization.

• 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 (e.g., AI‑assistant

• Deploy and monitor ML models in production with guardrails for performance, fairness, and safety.

• Run offline & online experiments (A/B and multivariate) to measure real-world outcomes such as engagement, match success rate, and conversation quality.

• Collaborate cross-functionally with platform engineers and product designers to integrate AI seamlessly into the Known user experience.

Requirements

• 3+ years in applied ML or data science engineering roles, ideally working on recommendation, search, or personalization systems.

• 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.

Example Projects

• Develop a user matching system based on profile information, onboarding transcripts and engagement behavior.

• Build a dynamic profile enrichment pipeline that integrates behavioral and linguistic features into user representations.

• Deploy a lightweight LLM-powered voice agent for user intake and conversational matchmaking.

• Create an evaluation harness combining offline metrics (AUC, NDCG) and online experiments (match acceptance, message rate).

• Build model monitoring and retraining loops informed by live interaction feedback.

Why This Role

This is an opportunity to define the technical DNA of a consumer AI product from day one — to architect and deploy systems that combine data science, human psychology, and generative AI. Your work will directly shape how people connect, communicate, and build relationships in an AI-assisted world.