Application Security Engineer | Mid-Senior | Low-level

We help people and businesses take back control of their online security, privacy, and data. From VPNs to password managers, threat intelligence to eSIMs for travel—our teams turn complex problems into solutions trusted by millions worldwide.

Life is online. In this role, you’ll help people own it.

Main Responsibilities

• Conduct security reviews of application designs, source code, and third-party libraries;
• Perform regular application vulnerability assessments using both automated tools and manual testing techniques (e.g., SAST, DAST, SCA, penetration testing);
• Collaborate with development teams to design secure architectures and implement security controls;
• Help maintain security tools, scripts, and processes to support secure development;
• Stay current with industry trends, zero-day vulnerabilities, and best practices in application security;
• Develop scripts, security automation tools to enhance application security testing processes;
• Design and deliver training for security engineering awareness & adoption;
• Actively look for internal security gaps within the product or organization overall.
• Ensure mobile/desktop applications are sufficiently tested and support internal and external audits;

• Proven experience in mobile/desktop application security assessment planning, testing, methodologies, and vulnerability reporting;
• Strong understanding of secure coding practices;
• Ability to perform manual security code audit;
• Proficiency in at least one low-level programming language (e.g. C, C++, Rust, Go).
• Solid understanding of networking protocols such as TCP, UDP and the HTTP protocol.
• Familiarity with debuggers (e.g. GDB, LLDB, WinDbg).
• Familiarity with reverse engineering tools (e.g. Ghidra, IDA).
• Solid understanding of memory corruption issues, buffer overflows and related vulnerability classes.
• Familiarity with common authentication and authorization protocols (OAuth, SAML, JWT, etc.).
• Ability to work with networking tools such as Wireshark, tcpdump.
• Ability to quickly assimilate new technologies and tools;
• Sense of ownership with strong problem solving and investigation skills;
• Ability to build and maintain relationships, influence key stakeholders across the business;
• Bonus points for community contributions like public CVEs, bug bounty recognition, open-source tools, blogs, etc.
  

• Sharpen your edge: training, mentorship, and room to grow — always.
• Take the time you need: extra vacation days, sick days, and time off when life calls.
• Get premium healthcare: private health insurance in Lithuania and Poland — fully covered.
• Protect your peace: enjoy free subscriptions to Calm, Headspace, and Mindletic, and our own resilience and mindfulness trainings.
• Own your fitness: in-house gyms, sport cards, online workouts, and personal guidance — on us.
• Pack your bags for workation: experience our company-wide trip abroad to the fullest.
• Work from anywhere: work from wherever keeps you in the zone.
• Celebrate your milestones: birthdays, weddings, and new family members — all deserve a gift.
• Parent with ease: children’s summer camps and flexibility around the schedule — because parenting never pauses.
• Join the party: team building and company events people talk about for months.
• Unlock Cyber City: coffee bar, open gyms, kids’ room, music room, massage chairs — our Vilnius HQ is yours to enjoy.

We expect all candidates to provide accurate and complete information during the recruitment process. While limited use of AI tools to refine application materials is acceptable, candidates remain fully responsible for ensuring that their submissions reflect their own qualifications, skills, and experience. Any failure to do so may negatively affect participation in the recruitment process. If broader AI assistance is allowed for a particular role or stage, we’ll let you know in advance.

By submitting your application, you acknowledge that it may be processed using automated tools for evaluation purposes. As part of our recruitment process, we may use an AI-based application review tool to help assess applications based on skills and experience relevant to the role. This technology is used to support - not replace - human decision-making, and every application is ultimately reviewed by a recruiter.

If you would like more information about how AI is used in this process or wish to exercise your rights under applicable data privacy laws, please contact us at [email protected]. Should you prefer to opt out of the automated evaluation, please submit your application directly to [email protected].