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: Remote in US and Europe
Principal VM Engineer – Workers Runtime Team
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.
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.
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.
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.
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).
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!