Application Security Engineer

Vestwell is the financial technology company powering the new savings economy. The New York City-based fintech platform redefines how people save for the critical aspects of life across retirement, education, and healthcare savings needs. Today, Vestwell enables over 790,000 businesses and more than 2.75 million active savers, with over $57 billion in assets saved across all 50 United States.  Vestwell offers a range of products, including workplace-delivered retirement plans, employer-offered student loan repayment benefits, and various savings accounts for education, emergencies, and individuals with disabilities. Vestwell's platform serves a diverse clientele, including financial advisers, employers, third-party administrators, financial institutions, payroll providers, government agencies, and individual savers. To learn more, visit  vestwell.com Who Are We Looking For? We are looking for an Application Security Engineer to help secure the applications and identity integrations that power our products. This role will focus on analyzing and protecting our NestJS applications, applying strong application security practices across the software development lifecycle, and supporting the security of our identity capabilities as both an identity provider (IdP) and a relying party (RP) in OIDC integrations and internal application usage. You will work closely with software engineering, platform, infrastructure, and product teams to identify risk, implement practical mitigations, and make secure-by-default development easier. The ideal candidate combines solid hands-on application security skills with a working knowledge of modern authentication and authorization protocols, and is eager to grow deeper expertise in identity security. What Will You Be Doing? Analyze NestJS and TypeScript applications for authentication, authorization, input validation, injection, session, API, business-logic, and data-protection vulnerabilities. Apply and help refine secure development patterns for NestJS, including guards, interceptors, middleware, decorators, validation, error handling, logging, configuration, and dependency management. Contribute to the security of our OIDC integrations and identity platform capabilities when we operate as: An identity provider, including authorization, token, user-info, discovery, key-set, and logout endpoints. A relying party, including client registration, redirect handling, authorization-code flows, token exchange, session establishment, and logout. Review OAuth 2.0 and OpenID Connect flows, including authorization code with PKCE, refresh tokens, client authentication, scopes, consent, state, nonce, redirect URI validation, and token lifetimes, under guidance from senior team members for more complex cases. Help apply and maintain authorization models using RBAC and, where appropriate, claims-based or policy-based access control. Review access-control boundaries across services, APIs, tenants, users, roles, permissions, and administrative functions. Participate in threat modeling, security design reviews, architecture reviews, and secure code reviews. Contribute to security requirements, reusable libraries, reference implementations, and developer guidance that reduce recurring risk. Support security testing and detection efforts, including SAST, DAST, software composition analysis, secret scanning, API testing, dependency monitoring, and targeted security testing. Partner with engineering teams to remediate vulnerabilities, help prioritize findings by exploitability and business impact, and verify fixes. Monitor relevant application and identity security signals, support incident investigations, and help maintain playbooks for account takeover, token compromise, authorization bypass, credential abuse, and related events. Help maintain security documentation, standards, risk exceptions, and evidence needed for audits and customer assurance. Stay current on application security, identity, OAuth/OIDC, browser security, API security, cloud security, and emerging attack techniques. Requirements The Necessities 2-4 years of professional experience in application security, product security, software engineering, or a closely related discipline. Experience securing Node.js and TypeScript applications; familiarity with NestJS is a strong plus. Working knowledge of OAuth 2.0 and OpenID Connect concepts and common implementation pitfalls. Exposure to IdP and/or RP implementations, integrations, or security assessments. Solid understanding of authentication and authorization concepts, including RBAC, least privilege, claims, scopes, permissions, sessions, and tokens. Ability to review code across APIs, web applications, and background jobs, with support from senior engineers on more complex architectural or distributed-systems questions. Familiarity with web and API security risks, including OWASP Top 10, OWASP API Security Top 10, broken access control, SSRF, injection, XSS, CSRF, insecure deserialization, and misconfiguration. Basic understanding of secure token handling, JWT validation, JWKS, signing algorithms, and token storage considerations. Some experience working with CI/CD and developer workflows, or a willingness to learn how to integrate security into them with minimal friction. Good communication skills and the ability to explain security findings and risk to technical teammates. A pragmatic, collaborative approach: eager to learn, ask good questions, and work with more senior engineers to propose and implement proportional controls. The Extras Exposure to identity platforms or libraries such as Auth0, Okta, Keycloak, Cognito, Azure AD/Entra ID, or comparable systems. Familiarity with SAML integrations for single sign-on solutions. Exposure to API gateways, microservices, event-driven systems, and cloud-native deployments. Familiarity with containers, infrastructure as code, secrets manage