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.

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: Aarhus, Denmark | Austin, TX | Lisbon, Portugal | London, UK | Munich, Germany

Principal VM Engineer – Workers Runtime Team

About the Department

The Emerging Technologies & Incubation (ETI) team at Cloudflare builds and launches bold, new products that push the boundaries of what’s possible on the internet. By leveraging Cloudflare’s massive network and edge computing capabilities, we solve complex problems at a scale few others can achieve.

About the Team

The Workers Runtime team is responsible for the execution environment that runs customer code at the edge. We focus on performance, security, and scalability, enhancing JavaScript APIs, WebAssembly support, and system optimizations to prepare for the next 10x scale increase. Our runtime operates in a resource-constrained, highly secure environment, requiring careful management of memory, CPU, and I/O.

What You'll Do

We are looking for a VM Engineer to help improve and embed the V8 virtual machine in our runtime. You’ll work on low-level optimizations, performance enhancements, garbage collection, and language support to ensure our platform remains cutting-edge. This role is ideal for engineers who love tackling high-performance, low-latency challenges in distributed environments.

Key Responsibilities

Optimize and embed the V8 VM within Cloudflare’s Workers Runtime.
Improve JavaScript execution performance and WebAssembly integration.
Debug, optimize, and enhance low-latency, real-time environments.
Ensure the reliability and efficiency of large-scale, Linux-based distributed systems.
Collaborate with engineers across runtime, security, and networking teams to push the boundaries of edge computing.

What We're Looking For

6+ years of professional experience with C++.
4+ years of hands-on VM/compiler experience, ideally with V8.
Strong knowledge of computer science fundamentals, including data structures, algorithms, and system architecture.
Experience with low-latency environments (e.g., game streaming, trading systems, high-performance computing).
Operational mindset – you build scalable, production-ready solutions.
Deep understanding of web technologies (HTTP, JavaScript, WASM).

Bonus Points

Experience working with Rust in high-performance distributed systems.
Familiarity with serverless platforms and cloud computing.
Deep knowledge of JS engine internals (V8, SpiderMonkey, JavaScriptCore).
Experience with standalone WebAssembly runtimes (Wasmtime, Wasmer, Lucet).
Strong expertise in Linux/UNIX systems, kernels, and networking.
Contributions to large open-source projects.

This is an exciting opportunity to work on cutting-edge compiler and runtime technologies at an unmatched scale. If you're passionate about high-performance computing, distributed systems, and compilers, we’d love to hear from you!

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!

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.