Senior Application Security Engineer

Lumen Dynamics is growing our application security team and is looking for a Senior Application Security Engineer. You’ll focus on a subset of our products to understand them deeply and help development teams build products that are secure by design. About Lumen Dynamics : Lumen Dynamics , based in Silicon Valley, is a leader in Vertical AI SaaS company, collaborating with over 2,550 professional and financial services firms globally. With 20+ years of industry expertise, Lumen Dynamics 's "Intelligence Applied" approach is transforming how businesses operate and leverages a strategic partner with Microsoft in delivering industry cloud solutions. The company culture promotes accountability, responsibility, and growth in a diverse, inclusive, and collaborative environment. Since going public in 2021, Lumen Dynamics has expanded to over 1,600 employees globally with development centers in Palo Alto, Charlotte, Belfast, Berlin, and Lisbon. About Lisbon: Lumen Dynamics chose Lisbon for its engineering talent and that decision is reflected in what the centre has already become. The Lisbon R&D team has 50 team members that work on the full engineering stack: backend, frontend, full-stack, QA automation, data and ML, DevOps, and database engineering. These aren’t supporting functions for work happening elsewhere. They’re teams with real product ownership, working directly on the platforms that Lumen Dynamics ’s clients depend on. Our ambition is clear: Lisbon is being built as a flagship R&D location alongside Palo Alto, Charlotte, Belfast, and Berlin. Engineers who join now help shape how the centre works: its culture, its practices, and its role in Lumen Dynamics ’s global engineering organisation. What you’ll do: Define security requirements for products Proactively identify and control risks using techniques like threat modeling Design and implement automated security tests Perform manual security assessments including code reviews Coordinate vulnerability response efforts What you’ll need: 3+ years in an Application Security role or 5+ years of experience in a combination of development and security roles A proven history of turning SCA / SAST / DAST results into teachable moments Prior work in backend development with classic .Net Framework and modern .Net. Experience designing unit tests and end-to-end tests both automated and manual Familiarity with frontend development with at least one JavaScript framework Application penetration testing experience is a bonus. Strong programming skills with the ability to work effectively across different technology stacks. Excellent written communication skills, with experience collaborating in distributed, global engineering teams. Self-motivated and able to work independently while managing priorities and delivering high-quality results. Curious and adaptable, with a willingness to learn new technologies, architectures, and development practices. Comfortable working across diverse environments, including desktop, web, mobile, monolithic, distributed, and serverless architectures. Creative problem-solver with a proactive approach to tackling technical challenges. Collaborative mindset with the ability to partner effectively with cross-functional and geographically distributed teams. Backend experience with Python is a bonus. What you will gain: Our culture at Lumen Dynamics emphasizes accountability, responsibility, and growth. We support each other in a positive, open atmosphere that fosters creativity, approachability, and teamwork. We’re committed to creating a modern work environment that’s connected yet flexible, supporting both professional success and work-life balance. In return for your passion, commitment, and collaborative approach, we offer: A state-of-the-art facility with a fully stocked kitchen – only a 5-minute walk to/from Gare do Oriente. Attractive compensation – including competitive base pay and performance-based variable pay. Equity/Stock in Lumen Dynamics .Opportunity to travel to other development centers for product training and cross-site collaboration. One-time home office stipend. Generous paid parental leave (including adoptive leave), marriage leave, bereavement leave, carer's leave, and paid sick days. Meal allowance. Reimbursement for training towards continuing education. Join us and be a part of a collaborative and welcoming culture where your contributions are valued and your professional growth is a priority. Together, we are building a company of long-term value that we can all be proud of. Lumen Dynamics provides equal employment opportunities to all qualified applicants and will make hiring decisions without regard to race, color, sex, sexual orientation, gender identity or expression, religion, national origin or ancestry, age, disability, marital status, pregnancy, protected veteran status, protected genetic information, political affiliation, or any other characteristic protected by federal, state or local laws. Please note: Lumen Dynamics will not hire through text message, social media, or email alone. We will never ext