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Kernel

Browser Security Engineer

San Francisco
Salary
$225K - $250K
Level
Mid
Work type
On-site · San Francisco

Not stated in the posting: visa.

Open. First seen 2 October 2026.

Apply on the company's site →

About the role

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.

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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.

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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.

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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.

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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

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Hiring process

Kernel's standard text

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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What this role asks for

Particular to this role

Linux · Networking

Rare in Kernel's other 10 open postings.

In most of Kernel's ads

Vercel

Named in most of its open postings, whatever the role.

95% of this description is written for the role. The rest is Kernel's standard text, folded away below.

Read against Kernel's other open postings on this site.

The team: Engineering

This role is one of 7 open in Engineering.

WHAT THE TEAM WORKS WITH, ACROSS ITS POSTINGS

Vercel (7 of 7), LLM (6 of 7), Docker (3 of 7), GitHub (3 of 7), Sentry (3 of 7), Supabase (2 of 7)

OTHER ROLES ON THIS TEAM

From the team and dates on Kernel's own job board.

See Security Engineer salaries in San Francisco →

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