MozillaHiring

Senior Software Engineer, Firefox Security

  • Remote, Belgium
  • Senior
  • Posted 2 weeks ago
Apply with Keywordise AI

or apply from Claude / ChatGPT / Muse

In one line

Security engineering role on a browser team, hardening the browser for enterprise users and improving its core security architecture.

About the role

The team works on browser security for enterprise customers and on the core mechanisms that keep the browser trustworthy. Good work here means fixes that hold up and features that ship.

At a glance

Pay
Not stated in the posting
Remote scope
Remote, Belgium
Seniority
Senior
Skills
Rust, HTML, CSS, JavaScript, WebPKI
Posted
14 Oct 2026
Last checked
28 Oct 2026

What you will do

  • Build and ship security and hardening features aimed at enterprise users
  • Improve core security architecture across operating systems, including privilege isolation and trust boundaries
  • Work with other teams to trace security issues to their root cause and land maintainable fixes
  • Diagnose stability, correctness, performance and memory problems in a multithreaded codebase

What they look for

  • At least 3 years in low-level software engineering, with strong C and/or C++
  • Solid grasp of security fundamentals
  • Familiarity with HTML, CSS and JavaScript, plus interest or experience in Rust
  • Comfort working in large multi-language codebases and with distributed teams

Benefits

  • Performance bonus, retirement contributions vested immediately, wellness days, home office stipend, learning budget and paid parental leave

How Keywordise applies for you

  1. 1Upload your CVAdd your CV once. It takes about a minute.
  2. 2Tailored to this jobKeywordise writes a CV and a cover letter for this job from your real experience.
  3. 3The form fills itselfName, email, experience and screening questions, field by field.
  4. 4Application sentYou get a receipt and follow it in your dashboard.

Apply with Keywordise AI7-day free trial, no card.

Apply from your AI assistant

Connect Keywordise to your assistant once, then send it the prompt. It applies for you.

ClaudeConnectorChatGPTConnectorMuseby Meta

Claude

  1. In Claude, open Settings, then Connectors, and choose Add custom connector.
  2. Name it Keywordise and paste the connector URL.
  3. Click Connect, log in to Keywordise and approve. Then send the prompt in a new chat.
Connector URL
https://keywordise.com/mcp

Disconnect any time in your Keywordise settings.

ChatGPT

  1. In ChatGPT, open Settings, then Connectors. On plans that need it, turn on developer mode first.
  2. Add a new connector with the connector URL and choose OAuth. Leave the client ID and secret empty.
  3. Log in to Keywordise and approve. Then send the prompt in a new chat.
Connector URL
https://keywordise.com/mcp

Disconnect any time in your Keywordise settings.

Muse

  1. Open Muse (muse.ai or the app) and send it the message below.
  2. If Muse asks how to sign in, answer OAuth. Open the sign-in link it sends, log in to Keywordise and approve.
  3. Send the prompt. Muse asks before it sends anything.
Message for Muse
Add a custom connector called Keywordise. It is a remote MCP server at https://keywordise.com/mcp and uses OAuth. Give me the sign-in link.

Muse is available in the US only for now.

Prompt
Apply to Keywordise job mbcptaiply
How to connect

Questions about this job

Is this a remote job, and where can I work from?

The posting lists it as remote for people in Belgium.

What does this job pay?

No pay range is stated in the posting.

What experience is needed?

It is a senior role. The posting asks for: at least 3 years in low-level software engineering, with strong C and/or C++; solid grasp of security fundamentals; familiarity with HTML, CSS and JavaScript, plus interest or experience in Rust. Skills it names include Rust, HTML, CSS, JavaScript.

How do I apply with Keywordise AI?

Press the Apply with Keywordise AI button and add your CV. Keywordise tailors your CV and cover letter to this posting and sends the application for you, with a free 7-day trial and no card.

More remote IT and software jobs

All remote IT and software jobs
MozillaRemote, Belgium
Apply with Keywordise AI