Principal Data Scientist, Detection

About Us

At Cloudflare, we are on a mission to help build a better Internet. Today the company runs one of the world’s largest networks that powers millions of websites and other Internet properties for customers ranging from individual bloggers to SMBs to Fortune 500 companies. Cloudflare protects and accelerates any Internet application online without adding hardware, installing software, or changing a line of code. Internet properties powered by Cloudflare all have web traffic routed through its intelligent global network, which gets smarter with every request. As a result, they see significant improvement in performance and a decrease in spam and other attacks. Cloudflare was named to Entrepreneur Magazine’s Top Company Cultures list and ranked among the World’s Most Innovative Companies by Fast Company.

At Cloudflare, we’re not looking for people who wait for a polished roadmap; we’re looking for the builders who see the cracks in the Internet that everyone else has simply learned to live with. We value candidates who have the instinct to spot a "normalized" problem and the AI-native curiosity to create a solution using the latest tools. Our culture is built on iteration, leveraging AI to ship faster today to make it better tomorrow, while ensuring that every improvement, no matter how small, is shared across the team to lift everyone up. If you’re the type of person who values curiosity over bureaucracy, and that AI is a partner in solving tough problems to keep the Internet moving forward, you’ll fit right in.

Available Locations- New York, London

About Us

At Cloudflare, we have our eyes set on an ambitious goal: to help build a better Internet. Today the company runs one of the world’s largest networks that powers trillions of requests per month. Cloudflare protects and accelerates any Internet application online without adding hardware, installing software, or changing a line of code. Internet properties powered by Cloudflare have all web traffic routed through its intelligent global network, which gets smarter with every request. As a result, they see significant improvement in performance and a decrease in spam and other attacks. Cloudflare was recognized by the World Economic Forum as a Technology Pioneer and named to Entrepreneur Magazine’s Top Company Cultures list.

We realize people do not fit into neat boxes. We are looking for curious and empathetic individuals who are committed to developing themselves and learning new skills, and we are ready to help you do that. We cannot complete our mission without building a diverse and inclusive team. We hire the best people based on an evaluation of their potential and support them throughout their time at Cloudflare. Come join us!

About the Role

Cloudflare’s Engineering Team is home to some of the industry’s top engineers, dedicated to building and scaling innovative software that handles a huge proportion of the Internet. Our Detection department sits at the heart of that mission: we identify automated, fraudulent, and malicious activity across the Internet and through our gateway. We develop advanced detection systems and machine learning models that operate at scale, collaborating with Product and Engineering teams across the company to protect our customers and stay ahead of the constantly evolving threat landscape.

Responsibilities

Lead the research, design, and evaluate detection models that identify automated, fraudulent, and malicious activity across Internet-scale data

Mentor others in how to uncover patterns and behaviors that distinguish adversaries from legitimate users.

Own the detection measurement framework, defining metrics and evaluation strategies for problems where ground truth is noisy, delayed, or contested.

Drive adoption of promising AI/ML techniques and represent Cloudflare in the broader research community.

Drive cross-functional partnerships with ML Engineers, Data Engineers, and Product; Influence roadmaps and align detection strategy with company priorities.

Shape long-term detection strategy, identifying gaps and opportunities that span multiple product areas.

Desirable Skills, Knowledge, and Experience

Fraud and bots at scale. You have experience across fraud, abuse, and/or bot detection on large, high-velocity traffic. You may focus on one, but you transfer instincts between them.

Strong fundamentals, fluent in data. You have solid applied statistics, machine learning, and AI methodology fundamentals. You choose the right technique for the problem, and are fluent with large-scale data.

You have at least 8-10 years of experience professionally working in Data Science, ML Engineering, or Software Engineering.

Demonstrated ability to make ambiguous, high-stakes technical decisions with incomplete information.

You are very comfortable with Python & SQL in production environments.

Bonus points

At home in ground truth ambiguity. Building detections when ground truth is scarce is the heart of this job. You make real progress with weak, delayed, or absent labels and you're energized by adversaries that fight back.

You don't burn signals. You understand (or are curious to learn) how to act on detections without tipping your hand, knowing that how you deploy and respond can erode your future visibility.

Pragmatic about complexity. You know when a simple solution beats a complex one, and you don't chase small gains at disproportionate cost.

Disciplined in code. You apply strong programming and engineering best practices in both research and production code.

Impact-driven and clear. You connect your work to business impact and communicate clearly across technical and non-technical stakeholders.

Compensation

Compensation may be adjusted depending on work location.

For New York City based hires: Estimated annual salary of $215,000 - $270,000.

Equity

This role is eligible to participate in Cloudflare’s equity plan.

Benefits

Cloudflare offers a complete package of benefits and programs to support you and your family. Our benefits programs can help you pay health care expenses, support caregiving, build capital for the future and make life a little easier and fun! The below is a description of our benefits for employees in the United States, and benefits may vary for employees based outside the U.S.

Health & Welfare Benefits

Medical/Rx Insurance

Dental Insurance

Vision Insurance

Flexible Spending Accounts

Commuter Spending Accounts

Fertility & Family Forming Benefits

On-demand mental health support and Employee Assistance Program

Global Travel Medical Insurance

Financial Benefits

Short and Long Term Disability Insurance

Life & Accident Insurance

401(k) Retirement Savings Plan

Employee Stock Participation Plan

Time Off

Flexible paid time off covering vacation and sick leave

Leave programs, including parental, pregnancy health, medical, and bereavement leave

What Makes Cloudflare Special?

We’re not just a highly ambitious, large-scale technology company. We’re a highly ambitious, large-scale technology company with a soul. Fundamental to our mission to help build a better Internet is protecting the free and open Internet.

Project Galileo : Since 2014, we've equipped more than 2,400 journalism and civil society organizations in 111 countries with powerful tools to defend themselves against attacks that would otherwise censor their work, technology already used by Cloudflare’s enterprise customers--at no cost.

Athenian Project : In 2017, we created the Athenian Project to ensure that state and local governments have the highest level of protection and reliability for free, so that their constituents have access to election information and voter registration. Since the project, we've provided services to more than 425 local government election websites in 33 states.

1.1.1.1 : We released 1.1.1.1 to help fix the foundation of the Internet by building