MozillaHiring

Senior Software Engineer, Firefox Security

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

or apply from Claude / ChatGPT / Muse

In one line

Security engineering role on the Firefox browser, building hardening features and improving core security across platforms; remote friendly.

About the role

The team works on enterprise security features and the browser's security architecture, including cryptographic protocols and web APIs. Good work means shipping maintainable fixes and improving stability in a large multithreaded codebase.

At a glance

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

What you will do

  • Design, test, and ship security and hardening features for enterprise users.
  • Improve core security mechanisms like cryptographic protocols and web APIs.
  • Investigate security issues across teams and deliver maintainable fixes.
  • Diagnose stability, performance, and memory problems in a multithreaded environment.

What they look for

  • 3+ years in low-level software engineering with strong C and/or C++ skills.
  • Solid grasp of security fundamentals and debugging multithreaded native apps.
  • Familiarity with HTML, CSS, and JavaScript, plus interest in Rust.
  • Experience working with distributed teams and clear technical communication.

Nice to have

  • Interest or experience in Rust.

Benefits

  • Performance-based bonus plans and generous retirement contributions with immediate vesting.
  • Quarterly wellness days, country holidays, birthday off, and home office stipend.

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 h6inyt5gfp
How to connect

Questions about this job

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

Yes, it is listed as remote, aimed at candidates in the United Kingdom.

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: 3+ years in low-level software engineering with strong C and/or C++ skills; solid grasp of security fundamentals and debugging multithreaded native apps; familiarity with HTML, CSS, and JavaScript, plus interest in Rust. Skills it names include Rust, HTML, CSS, JavaScript.

How do I apply with Keywordise AI?

Select Apply with Keywordise AI, sign up and upload your CV. Keywordise writes a CV and a cover letter for this job from your real experience and applies for you. The 7-day free trial needs no card.

More remote IT and software jobs

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