Senior Data Infrastructure Engineer (Web-Scale Crawling Systems)

Our Mission

Reflection is a research lab making intelligence open and accessible for everyone to use, customize, and build on. We build open models that let anyone control their intelligence and help shape the future of AI. Our mission: make intelligence open and accessible to all.

About The Role

The web is one of the most important sources of information for frontier AI systems. The quality, coverage, freshness, and diversity of web data directly influence model capabilities.

As a member of the Data Team, your mission is to build and operate large-scale web crawling systems that continuously discover, acquire, and process content from across the internet. You will own the infrastructure that powers web-scale data collection, from URL discovery and scheduling to distributed crawling, content extraction, and dataset delivery.

You will work directly with world-class researchers to understand which parts of the web matter most for model performance and build systems that efficiently acquire high-value content at scale.

This role is ideal for engineers who love building distributed systems, optimizing large-scale crawlers, and solving the unique technical challenges of collecting data from the modern web.

What You’ll Do

Working closely with our pre-training, infrastructure, and data quality teams, you will:

• Build and operate web-scale crawling infrastructure capable of continuously collecting data across billions of URLs
• Design and optimize URL discovery, prioritization, scheduling, and crawl orchestration systems
• Develop distributed crawlers that efficiently acquire content while respecting site constraints and operational requirements
• Build systems for content extraction, rendering, parsing, and normalization across diverse web formats
• Improve crawl coverage, freshness, efficiency, and quality through measurement and experimentation
• Design infrastructure for large-scale recrawling, change detection, and incremental updates
• Develop specialized crawlers for high-value domains, dynamic websites, and difficult-to-access content sources

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• Analyze crawl performance and web coverage to identify gaps, inefficiencies, and opportunities for improvement
• Build observability, monitoring, and reliability systems for large-scale crawl operations
• Debug production issues and continuously improve the performance, scalability, and resilience of crawling infrastructure
  
  

About You

• Passionate about web-scale systems and the challenges of collecting information from the internet
• Curious about how web data influences model capabilities and willing to iterate based on downstream results
• Comfortable balancing crawl quality, coverage, freshness, and operational efficiency
• Enjoy working at the intersection of distributed systems, data infrastructure, and AI
• Able to collaborate closely with researchers, infrastructure engineers, and data quality teams
  
  

Skills And Qualifications

• Experience building large-scale web crawling, search indexing, content acquisition, or internet-scale data collection systems

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• Strong understanding of crawling architectures, URL frontier management, scheduling, and distributed crawl coordination
• Experience with large-scale distributed systems using technologies such as Ray, Spark, Beam, Flink, or similar frameworks
• Familiarity with content extraction, HTML parsing, browser automation, rendering systems, and modern web technologies
• Experience operating systems that process petabyte-scale datasets
• Strong systems engineering skills, including reliability, observability, performance optimization, and debugging
• Experience designing experiments and using data to improve crawl quality, coverage, and efficiency
• Excellent communication skills and the ability to reason clearly about system tradeoffs and operational constraints
  
  

Nice to Have

• Experience building search engines, web indexes, or internet-scale crawling platforms
• Familiarity with anti-bot systems, dynamic web content, browser automation, and large-scale extraction pipelines
• Understanding of how web data is used in training and evaluating large language models
• Experience with distributed storage systems, content deduplication, and web-scale dataset management
  
  

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What We Offer

We believe that to make intelligence open and accessible to all, you need to start at the foundation. Joining Reflection means building from the ground up as part of a talent-dense team. You will help define our future as a company, and help define the future of open foundational models.

We want you to do the most impactful work of your career with the confidence that you and the people you care about most are supported.

• Top-tier compensation: Salary and equity structured to recognize and retain our talent globally.
• Stock options: Everyone who joins and contributes to Reflection's success gets to share in the upside through stock options.
• Health & wellness: Comprehensive medical, dental, vision, and life, with an annual wellness allowance.
• Meals: Lunch and dinner are provided in the office daily.
• Life & family: 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys.
• Vacation days: Unlimited paid time off in the U.S. and 30 days in the U.K.
• Sponsorship support: We sponsor visas to help exceptional talent join our team and support long-term immigration pathways where applicable.
• Team building: We have regular off-sites, happy hours, and team celebrations.
  
  

Export Control Notice: This position may require access to technology or source code subject to the U.S. Export Administration Regulations. Any offer of employment for this role may be conditioned on the Company's ability to provide the candidate with access to such technology or source code in compliance with applicable U.S. export control laws, which may require the Company to seek government authorization.