Senior ML Engineer - Search & Ranking Systems

Perplexity; Greater London; On-site; GBP 90,000 - 130,000; Full time

Job summary

Perplexity is seeking an experienced Machine Learning Engineer to improve search quality across the middle and later stages of ranking. You will own ranking-quality problems end to end, from evaluation to deployment, tackling ambiguous challenges with a focus on production systems.

The role requires deep ML and software-engineering skills, a background in neural or low-latency ranking methods, and at least 5 years of industry experience in a data-driven environment.

Qualifications

• Deep understanding of search or recommender systems and their evaluation.
• Proven ownership of a large-scale production ranking system or a substantial class of quality problems.
• Strong machine-learning and software-engineering skills across data, models, serving, and monitoring.
• Ability to drive ambiguous, cross-team problems without continuous task decomposition.
• Exceptional depth in either modern neural ranking methods or low-latency ranking systems and runtime.
• Minimum 5 years of relevant industry experience.

Responsibilities

• Relentlessly push search quality forward through models, data, evaluation, infrastructure, or any other leverage available.
• Own ranking-quality problems end to end: define the evaluation, identify the bottleneck, build the solution, and ship it safely.
• Train and evaluate retrieval, ranking, and classification models, including neural and LLM-based approaches where appropriate.
• Build and operate ranking infrastructure, including feature computation, low-latency inference, multi-stage cascades, deployment, and monitoring.
• Make sound trade-offs across quality, latency, reliability, cost, and engineering complexity.
• Collaborate across Data, AI, Infrastructure, and Product while retaining ownership of the final quality outcome.

Skills

Search systems

Production ranking

ML & software engineering

Ambiguity handling

Neural ranking / low-latency

Experience

Job description

Perplexity is seeking an experienced Machine Learning Engineer to improve search quality across the middle and later stages of ranking. You will own ranking-quality problems end to end, from evaluation to deployment, tackling ambiguous challenges with a focus on production systems.

The role requires deep ML and software-engineering skills, a background in neural or low-latency ranking methods, and at least 5 years of industry experience in a data-driven environment.