Senior Software Engineer, Zero Trust Client

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: Austin, Seattle

About the role

We’re looking for a Senior Windows Software Engineer to join our Zero Trust team. You will be working on the Zero Trust desktop client, which protects corporate devices by securely and privately sending traffic from those devices to Cloudflare’s global network, which can apply advanced web filtering and advanced Zero Trust policies.

What you'll do

In your role, you will predominantly be using Rust along platform-native languages & APIs to implement high-performance networking code that runs on multiple desktop platforms. You’ll be expected to improve the code quality and to build solid, testable, and well-documented foundations. You will be most successful in this role if you have a good understanding of Windows internals (virtual memory, multi-threading, process lifecycle, kernel programing, system APIs, etc.) and networking protocols (TCP/IP, UDP, DNS, QUIC, H/3, proxying, etc.). You will also have to interact with other languages, such as Swift, C#, C, and python.

As a Senior Software Engineer, you will be expected to make significant contributions to the design and implementation of major development projects, working closely with our product managers and other teams to implement customer-impacting features. You will work on stimulating problems born out of the scale of our deployment, and the stringent quality, performance, and security requirements of our product.

Desirable Skills, Knowledge, and Experience

In-depth knowledge of Windows internals, kernel-mode programming, and network protocols

Experience in low-level Windows driver development, ideally network drivers

Excellent programming skills, with experience writing very high-quality and low-complexity code with thorough documentation.

Strong experience writing easily-testable and thoroughly-tested code (e.g. using dependency injection with the right abstractions)

Great experience using lower-level languages, such as Rust, C, C++

Very comfortable writing multithreaded, asynchronous code

Strong experience with debugging network-related problems

An understanding of how VPN technologies work, and the trade-offs between privacy, security, and anonymity

Good understanding of, and experience with, security protocols and standards

Experience mentoring engineers and raising a team's technical bar through code review and knowledge sharing

Experience owning technical designs end-to-end, writ