Staff Application Security Engineer

OverviewJoin to apply for the Staff Application Security Engineer role at LEDN . Ledn is a global financial services company built for digital assets, helping to improve the everyday lives of Bitcoin holders while building generational wealth for the future. Ledn offers a suite of egalitarian lending, savings, and trading products to digital asset holders in over 150 countries. The team is a passionate group from diverse backgrounds with a shared conviction that digital assets can democratize access to the global economy. Core values: act with integrity, own it, have a passion for progress, and lead with empathy. Come join us as we build, innovate and revolutionize financial services. The OpportunityWe are seeking a full-time Staff Application Security Engineer with deep expertise in Application Security, Identity & Access Management, and Confidential Computing to strengthen the security of our Bitcoin-backed loan platform. Security is fundamental to protecting our customers and business, and this role will drive both tactical improvements and long-term strategy for securing our applications and authentication systems. You will work across our JavaScript/TypeScript services, AWS serverless stack (Lambda, API Gateway, Cognito, SNS, SQS), MongoDB and Kubernetes microservices, and take ownership of evolving our authentication layer toward modern, phishing-resistant approaches. You will also design and operate AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated, verifiable environments. This is a hands-on engineering role with direct impact on product security, infrastructure security, and customer trust. ResponsibilitiesLead secure design and code reviews across engineering teams. Define and enforce secure coding practices for JavaScript/TypeScript services. Automate vulnerability detection (SAST, SCA, DAST) within CI/CD. Conduct threat modeling and risk assessments for new features. Partner with engineers to remediate vulnerabilities and improve secure development practices. Own the roadmap for authentication and identity across customer and internal applications. Enhance Cognito-based identity architecture with stronger, phishing-resistant MFA solutions (e.g., WebAuthn, passkeys, hardware tokens). Collaborate with Product to align usability, compliance, and security in authentication flows. Define secure approaches to session management, device trust, and account recovery. Design enclave-based architectures to isolate and protect sensitive workloads using AWS Nitro Enclaves; integrate with KMS and secure APIs; migrate high-value operations into enclave environments. Ensure compliance, auditability, and resilience of enclave workloads. Harden AWS services (Lambda, API Gateway, SQS, SNS) with least-privilege IAM and secure key management. Improve Kubernetes security posture (RBAC, pod security, image scanning, runtime monitoring). Deploy and operate a SIEM framework; develop detection rules, dashboards, and incident playbooks. Support compliance initiatives (SOC 2, ISO 27001) with security controls and documentation. What You Bring to Ledn10 years minimum of proven experience in Application Security with a focus on web and cloud-native applications. Strong knowledge of JavaScript/TypeScript/Golang/Python and modern web vulnerabilities (OWASP Top 10, auth bypasses, business logic flaws). Expertise with AWS security best practices, particularly in serverless architectures. Hands-on experience with AWS Nitro Enclaves for confidential computing. Deep understanding of authentication and authorization standards (OAuth2, OIDC, WebAuthn, FIDO2). Practical experience with Cognito / Auth0 (MFA, custom flows, secure session handling). Background in SIEM design and log correlation across cloud and application layers. Familiarity with Kubernetes security (RBAC, pod security, admission controls, image scanning). Experience with Secure Code Review and understanding of software supply chain. Strong understanding of Linux internals and remediation of vulnerabilities identified in penetration tests. Strong communication and collaboration skills to influence engineering and product teams. Nice to HavesFamiliarity with Bitcoin custody and key management practices. Knowledge of Infrastructure as Code security (Terraform, AWS CDK). Prior work on user-facing security features such as passwordless authentication, recovery flows, or device trust. Culture FitWe’re looking for a leader who thrives in a startup or tech environment and embodies our values. The ideal candidate will be adaptable, resilient, collaborative, and able to navigate ambiguity in a high-growth, fast-paced environment. Benefits and PerksComprehensive total rewards package starting on your first day. Competitive PTO and ownership in the company through shared equity, with remote work flexibility up to 180 days per year (subject to restrictions). A career with purpose and a focus on removing barriers so you can do your best work. Equal OpportunityLedn is an equal opportunity employment organization and prides itself on inclusivity, diversity, and the success that comes from diversity. You may reach out to the Ledn team by emailing for accommodation requests throughout all stages of the recruitment process. Requests will be addressed confidentially. NotesLedn’s team is global, with employees across North America, Latin America, South Africa and Europe. We are a remote-first company. Please note that due to high volume, only qualified applicants will be contacted. Shortlisted candidates may be asked to submit a short video response and we may review publicly available social media activity relevant to the role. No agencies or recruiters, and Ledn does not accept unsolicited agency resumes or fees related to unsolicited resumes. #J-18808-Ljbffr