Browser Security Engineer

About KernelKernel 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 salaryAbove market equityPremium medical + dental coverage + dependent coverageSmall, trusting team of senior + staff engineersDefault async with minimal bureaucracyDaily lunches on usUnlimited PTO401k + company matchRelocation 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!