Browser Security Engineer

San Francisco, CAOnsiteFull Time$225,000–$250,000 /yrPosted 2 months agoVisa sponsorship available

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Required skills

Chromium
browser sandboxes
renderer stacks
network stacks
Linux kernel
microVMs
Firecracker
Cloud-Hypervisor
Kata
gVisor

Nice to have

browser hardening
security engineering

Role summary

Kernel is seeking a Browser Security Engineer to enhance and secure their open-source, AI agent-focused browser infrastructure built on Chromium. This role involves deep work with sandboxing, networking, and virtualization technologies, including debugging and optimizing Chromium builds within microVM environments. Responsibilities include implementing network isolation, collaborating on kernel-level security, building analysis tools, and ensuring secure supply chains. The ideal candidate has strong familiarity with Chromium internals, Linux kernel, microVMs, low-level debugging tools, and networking fundamentals. Experience in security engineering or browser hardening is a plus.

About Kernel

Kernel is crazy fast, open source browser infrastructure for AI agents. We handle autoscaling, observability, and the messy details of web interaction, so developers can focus on what their agents do instead of how they do it.
Teams at Cash App, Framer, and 7000+ others use Kernel for deep research, QA automation, and real-time web analysis. We've raised $22M from Accel, YC, and Vercel.
If you're interested in building critical infrastructure for agents on the web, we'd love to chat.

About the role

We’re hiring a Browser Security Engineer to harden and extend our Chromium-based browser runtime. You’ll work at the intersection of sandboxing, networking, and virtualization — ensuring our browsers run securely and efficiently across thousands of concurrent users.

What you’ll do
Debug, patch, and optimize Chromium builds running inside Kernel’s microVM environments.
Implement and maintain network isolation, proxy routing, and IP handling for browsers.
Collaborate with infra engineers on unikernel-based isolation, process scheduling, and kernel security policies.
Build internal tooling for binary analysis, crash triage, and vulnerability monitoring.
Support the team in maintaining secure supply chain and reproducible builds for our browser images.

What we’re looking for
Deep familiarity with Chromium internals, browser sandboxes, or renderer/network stacks.
Experience with Linux kernel, microVMs (Firecracker, Cloud-Hypervisor, Kata, gVisor, etc.), or container isolation.
Strong debugging skills with strace, gdb, perf, or similar low-level tools.
Knowledge of networking fundamentals (DNS, TCP/IP, NAT, proxies, TLS).
Background in security engineering or browser hardening a plus.

What you can expect as a Kernel
Industry-competitive salary
Above market equity
Premium medical + dental coverage + dependent coverage Small, trusting team of senior + staff engineers Default async with minimal bureaucracy Daily lunches on us Unlimited PTO 401k + company match Relocation assistance

Hiring process
We have a simple process focused on real world collaboration and jointly getting to know each other:
30 minute intro calls with one of Kernel’s co-founders 45-minute technical interview (virtual) Half-day on-site (in-person) working with our team on relevant technical challenges.
Offer!

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