Senior Web Security Engineer, Browser Platform

Working on the Security Functional Team, you’ll play a pivotal role in ensuring our security capabilities keep pace with our rapid product development, including our expanding AI offerings like Duck.ai and agentic browsing, directly protecting our users across all our products. You’ll also maintain incident detection and response capabilities for the company, and work on related projects. Recent projects include:

• SERP security mitigations
• Agentic browsing security mitigations
• Agentic browser hardening
• Browser and sync security audits

As a Senior Security Engineer, App Sec , you’ll execute on SERP security mitigations (XSS prevention, tooling development to help engineers write safer code), manage application security scanning infrastructure setup, build and maintain harnesses that get security fixes out automatically, harden our agentic browsing and DuckAI experiences against emerging threats (like prompt injection), conduct browser and sync security audits (special pages, DuckAI integrations, password manager, etc.), deliver on internal red-team operations (simulated attack scenarios), support security triage, and more!, * You’ll be required to attend meetings on camera via video conferencing

• Expect to travel at least two times a year: once for our all-hands meetup and again for a team retreat (each around 4-5 days). While extenuating circumstances may impact attendance, everyone is strongly encouraged to attend.
• While we offer a flexible work arrangement with no core hours, expect an average full-time commitment of 40 hours per week.
• A successful candidate must pass a background check as a condition of joining the team.
• By applying for this role, you confirm that all information submitted is accurate and complete. You further acknowledge that providing false or fraudulent information during the application process is cause for denial of an offer, revocation of any existing offer, or other adverse action, up to and including termination after the start of your commencement of work.

Disclosure Statement: Use of AI in Hiring Process

As part of our commitment to enhancing our recruitment process, we utilize artificial intelligence (AI) technology to assist in reviewing and summarizing job applications and test projects, including those tools integrated into our recruitment vendor platforms. We use AI to flag potentially fraudulent applications, analyze and summarize applicants’ experience, interviews, and project performance, and help streamline our selection process.

Key Principles:

• Data Privacy: All information provided in your application will be handled in accordance with our Recruiting Privacy Policy . We ensure that your personal information is protected and used solely for recruitment purposes.
• Human Oversight and Accountability: The AI technology is designed to support our hiring team by providing insights and summaries of applications and evaluations of test projects against scoring rubrics. All final evaluations and hiring decisions, however, will be made by our hiring team, who will consider the AI’s input alongside other factors.
• Transparency: We believe in transparency regarding our hiring practices. If you have any questions about how AI is used in our recruitment process, please feel free to reach out to us.

• 7+ years of experience in web or application security (performing security assessments, vulnerability research, penetration testing, or secure code review)
• Recent experience creating security focused agentic harnesses
• Experience influencing large feature designs to have security baked in from the start
• Advanced programming or scripting experience with JavaScript. Any additional experience with our stack is a bonus: Swift/Kotlin/C#/JavaScript (native apps) or JavaScript/Perl/Go (search).
• An understanding of the web security model (such as the Same Origin Policy); experience with CSP, CORS, SameSite cookies, sec-fetch-*, CORB, CORP, Sanitizer API, and Trusted Types is beneficial
• Hands-on experience identifying and exploiting web vulnerabilities (XSS, CSRF, injection attacks, authorization flaws, etc.)
• Familiarity with security testing tools and frameworks
• Experience partnering and collaborating with Product Engineers, advising on security matters and helping teams ship secure code faster
• Experience shaping how an organisation thinks about security - driving best practices, improving processes, and raising the bar across teams

Compensation is transparent across the organization, and all team members within the same professional level and global region receive the same compensation, plus stock options:

• United States: $190,500 USD
• United Kingdom: £134,600 GBP
• Canada: CA$253,500 CAD
• All other regions*: €157,350 EUR

*Team members outside the US, UK and Canada are currently paid $178,500 USD. Pay converts to the EUR amount above on January 1, 2027 for Spanish team members, and approximately February 1, 2027 in all other regions.

Eligibility for company-sponsored health benefits is limited to team members based in the United States. This program does not extend to team members located in other countries, such as Canada or the UK.

Hi, we’re DuckDuckGo, the online protection company and remote-first team of 400+ on a mission to raise the standard of trust online. Founded in 2008 and profitable since 2014, our annual revenue is in the hundreds of millions USD and millions use our browser on Mac , Windows , iOS , and Android , our search engine , and the DuckDuckGo subscription . We also offer private, useful, and optional AI, including Duck.ai , which lets you chat privately with ChatGPT, Claude, and other AIs, all in one place.

Our culture of trust, inclusivity, and empowered project management underpins everything we do, where each team member takes full ownership of their projects, from scoping and execution to postmortem. If you’re seeking end-to-end ownership of your work, you’ve come to the right place!, Hiring works best when it’s a two-way street. Learn how we help you get to know DuckDuckGo, envision your future role here, and find out more about how we hire .