Browser Engineer

Cintrifuse; San Francisco (CA); On-site; USD 180,000 - 300,000; Full time

Benefits offered by this job

Competitive salary

Equity

Medical coverage

Dependent coverage

Senior team

Async culture

Daily lunches

Unlimited PTO

401k match

Relocation assistance

Job summary

Kernel is a fast, open source browser infrastructure for AI agents. You will harden and extend our Chromium-based browser runtime, working across sandboxing, networking, and virtualization to secure and optimize browser execution for thousands of concurrent users.

As a Browser Engineer, you’ll debug, patch, and improve Chromium builds inside microVM environments, implement network isolation, and collaborate with infra engineers on isolation policies and secure build processes.

Qualifications

• 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.

Responsibilities

• 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.

Skills

Chromium internals

Linux kernel

microVMs

debugging tools

networking fundamentals

security engineering

Job description

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 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:

1. 30 minute intro calls with one of Kernel’s co-founders


2. 45-minute technical interview (virtual)


3. Half-day on-site (in-person) working with our team on relevant technical challenges.


4. Offer!