Principal Data Scientist, Detection

Cloudflare; Deutschland; On-site; EUR 185,000 - 233,000; Full time

Benefits offered by this job

Equity plan

Comprehensive benefits

Job summary

Cloudflare is seeking an experienced ML/Data Science professional to lead detection research and engineering efforts focused on identifying automated, fraudulent, and malicious activity at Internet scale. You will mentor teammates and own the measurement framework while driving adoption of advanced AI/ML techniques across the organization.

You’ll collaborate with ML Engineers, Data Engineers, and Product teams to align detection strategy with company priorities and build scalable solutions that

Qualifications

• Fraud, abuse, and/or bot detection on large, high-velocity traffic experience.
• Solid applied statistics, ML/AI fundamentals; choose appropriate technique for problems.
• 8–10 years of professional experience in Data Science, ML Eng, or Software Eng.
• Ability to make ambiguous, high-stakes technical decisions with incomplete information.
• Fluent in Python and SQL in production environments.

Responsibilities

• Lead research, design, and evaluate detection models for automated, fraudulent activity at Internet scale.
• Mentor others in uncovering patterns that distinguish adversaries from legitimate users.
• Own the detection measurement framework with metrics and evaluation strategies.
• Drive adoption of AI/ML techniques and represent Cloudflare in the research community.
• Foster cross-functional partnerships with ML Engineers, Data Engineers, and Product; align detection strategy with priorities.
• Shape long-term detection strategy across multiple product areas.

Skills

Fraud and bots at scale

Data fundamentals

Senior-level experience

Ambiguity handling

Python & SQL in production

Tools

Python

SQL

Job description

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 a faster, more secure and privacy‑centric public DNS resolver. This is available publicly for everyone to use - it is the first consumer‑focused service Cloudflare has ever released. Here’s the deal - we don’t store client IP addresses never, ever. We will continue to abide by our privacy commitment and ensure that no user data is sold to advertisers or used to target consumers.

Sound like something you’d like to be a part of? We’d love to hear from you!

Please note that applicants who progress to the offer stage of the interview process may be asked to attend an in-person interview within one of the Cloudflare Offices or Cloudflare Hubs. More details about this will be available at that stage of the interview process.

This position may require access to information protected under U.S. export control laws, including the U.S. Export Administration Regulations. Please note that any offer of employment may be conditioned on your authorization to receive software or technology controlled under these U.S. export laws without sponsorship for an export license.

Cloudflare is proud to be an equal opportunity employer. We are committed to providing equal employment opportunity for all people and place great value in both diversity and inclusiveness. All qualified applicants will be considered for employment without regard to their, or any other person's, perceived or actual race, color, religion, sex, gender, gender identity, gender expression, sexual orientation, national origin, ancestry, citizenship, age, physical or mental disability, medical condition, family care status, or any other basis protected by law. We are an AA/Veterans/Disabled Employer.

Cloudflare provides reasonable accommodations to qualified individuals with disabilities. Please tell us if you require a reasonable accommodation to apply for a job. Examples of reasonable accommodations include, but are not limited to, changing the application process, providing documents in an alternate format, using a sign language interpreter, or using specialized equipment. If you require a reasonable accommodation to apply for a job, please contact us via e-mail at [e-mail] or via mail at 101 Townsend St. San Francisco, CA 94107.