Senior ML Engineer: Search, Retrieval & LLMs

Perplexity; Greater London; Hybrid; GBP 90,000 - 120,000; Full time

Job summary

Perplexity is seeking an experienced Machine Learning Engineer to help build the next generation of advanced search technologies, with a focus on retrieval and ranking.

You will architect core components of our search platform and model stack, train and evaluate retrieval, ranking and classification models (including LLMs), and deploy scalable models from boosting to LLMs in production. Expect collaboration across Data, AI, Infrastructure and Product teams for fast, high-quality delivery.

Qualifications

• Deep understanding of search and retrieval systems with evaluation metrics.
• Proven track record with large-scale search or recommender systems.
• Self-driven with ownership and execution.
• Minimum of 5 years of working on search or recsys-related projects.

Responsibilities

• Relentlessly push search quality forward—through models, data, tools, or any leverage available.
• Architect and build core components of our search platform and model stack.
• Train and evaluate retrieval, ranking and classification models, including LLMs.
• Deploy models—from boosting to LLMs—in a scalable and performant way.
• Build and optimize RAG pipelines for grounding and answer generation.
• Collaborate with Data, AI, Infrastructure and Product teams to ensure fast and high quality delivery.

Skills

Search & retrieval systems

Large-scale search/recSys

Ownership & execution

5+ years experience

Job description

Perplexity is seeking an experienced Machine Learning Engineer to help build the next generation of advanced search technologies, with a focus on retrieval and ranking.

You will architect core components of our search platform and model stack, train and evaluate retrieval, ranking and classification models (including LLMs), and deploy scalable models from boosting to LLMs in production. Expect collaboration across Data, AI, Infrastructure and Product teams for fast, high-quality delivery.