This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Software Development Engineer - UI/UX based in the United States. Join a mission-driven engineering team developing advanced cybersecurity solutions that help protect critical infrastructure from evolving digital threats. In this senior engineering role, you will build and maintain intuitive web applications, robust APIs, and client SDKs that help security professionals identify and understand exploitable software vulnerabilities. You will work across frontend development, API architecture, and developer tooling, contributing throughout the entire software delivery lifecycle. Collaborating closely with Product, Design, and backend engineers, you will translate complex technical data into clear, accessible user experiences. You will also help ensure that APIs and SDKs remain reliable, secure, and compatible as the platform evolves. This remote-first opportunity is ideal for an experienced engineer who values technical ownership, thoughtful collaboration, and meaningful real-world impact.