Member of Technical Staff (Machine Learning Research Engineer)

Perplexity·Berlin, Berlin, Germany·posted 12d ago · last seen 29m ago

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About interviewing at Perplexity

One of the few AI startups with a fully published interview guide (perplexity.ai/hub/careers/interview-guide): online application (response within two weeks) → recruiter phone screen → a technical screen that for engineers is 'usually a standard technical programming interview' → a quickly-scheduled onsite of 4–5 interviews including a hiring-manager deep dive on past work and experience anecdotes → a final interview with a Perplexity founder or leader → decision within a week of the onsite. Coding leans Python and mixes LeetCode medium–hard with practical search-flavored tasks (ranking/filtering, concurrency, data handling); system design is AI-native (RAG pipelines, retrieval at scale, LLM serving cost/latency). Applicants are judged 'solely on merit and potential impact' and must show 'frontier knowledge and excellence in at least one area'; roles are broad by default with team matching happening during the onsite, every role — managers included — is hands-on, and building AI products isn't expected but fluency in using AI tools is required. In-person 4 days/week near an office; remote is case-by-case.

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Description

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

Responsibilities

  • Relentlessly push search quality forward — through models, data, tools, or any other leverage available

  • Architect and build core components of the search platform and model stack

  • Design, train, and optimize large-scale deep learning models using frameworks like PyTorch, leveraging distributed training (e.g., PyTorch Distributed, DeepSpeed, FSDP) and hardware acceleration, with a focus on retrieval and ranking models

  • Conduct advanced research in representation learning, including contrastive learning, multilingual, and multimodal modeling for search and retrieval

  • Deploy models — from boosting algorithms 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

Qualifications

  • Deep understanding of search and retrieval systems, including quality evaluation principles and metrics

  • Proven track record with large-scale search or recommender systems

  • Strong proficiency with PyTorch, including experience in distributed training techniques and performance optimization for large models

  • Expertise in representation learning, including contrastive learning and embedding space alignment for multilingual and multimodal applications

  • Strong publication record in AI/ML conferences or workshops (e.g., NeurIPS, ICML, ICLR, ACL, CVPR, SIGIR)

  • Self-driven, with a strong sense of ownership and execution

  • Minimum of 3 years (preferably 5+) working on search, recommender systems, or closely related research areas

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