Senior Software Engineer, Bots + Fraud Detection (EMEA) in London

About Us

At Cloudflare, we are on a mission to help build a better Internet. Today the company runs one of the worlds 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 Worlds Most Innovative Companies by Fast Company. 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!

Available Locations: Lisbon or London (EMEA)

About the department

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 team responsible for Bots and Fraud Detection develops cutting‑edge solutions to identify and mitigate malicious bot activities, ensuring the security and integrity of online applications. The team collaborates with product and other engineering teams to implement advanced fraud detection mechanisms and employ machine learning techniques to safeguard digital assets from evolving threats in the cybersecurity landscape.

What you'll do

• Join Cloudflare's Bot and Fraud Detection team to tackle real‑world security challenges, leveraging massive threat intelligence data through data science and machine learning.
• Design, build, and scale high‑performance distributed software for one of Cloudflare's fastest‑growing security products.
• Work with global data exceeding 50 million HTTP requests per second, utilizing a tech stack that includes Go, Python, JavaScript, Rust, Lua, Kafka, Kubernetes, ClickHouse, PostgreSQL, and Jupyter notebook.
• Make a meaningful impact in detecting and mitigating abusive HTTP L7 layer traffic worldwide.

What are we looking for?

• Proficiency in designing, integrating, and optimizing distributed data processing pipelines.
• Strong coding skills in Go, Java, Python, or other high-performance languages.
• Experience in constructing and managing alerting and monitoring systems for data processing pipelines.
• Exceptional abilities in systems‑level debugging.
• Preferred background or interest in Web Security, HTTP protocols, and JavaScript.
• Familiarity with advanced analytics encompassing machine learning, statistical inference, and AI.
• Curiosity and empathy.
• Comfortable with tackling ambiguous problems and unblocking yourself.

Bonus Points

• Knowledge and experience with columnar database like Clickhouse.
• Experience productionalizing ML models.
• Experience with cluster and configuration management systems such as Docker, Salt.
• Strong web security fundamentals.
• Previous experience in bot and fraud detection.

What Makes Cloudflare Special?

We aren’t 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 would love to hear from you!

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 hr@cloudflare.com or via mail at 101 Townsend St. San Francisco, CA 94107.