Senior Application Security Engineer

Join to apply for the Senior Application Security Engineer role at RainRain is the fastest-growing earned wage access (EWA) fintech in the U.S., serving 3.5 million employees and backed by top investors like QED and Prosus.
We have raised nearly $400M in funding—including the largest Series A in fintech history—and just closed our Series B to fuel our next stage of hypergrowth.
We are seeking a skilled and driven Senior Application Security Engineer to join Rain's growing Security team.This role is technically grounded and requires direct engagement in application-layer matters and security reviews, while contributing to cloud security automation, awareness initiatives, and secure engineering practices across the SDLC.
You will partner closely with engineering and development squads and work alongside our Cloud Security and GRC teams to improve Rain's application and platform security posture.Key ResponsibilitiesCollaborate with development squads to validate vulnerabilities and provide actionable remediation guidance aligned with business risk.Drive threat modeling sessions (e.g., STRIDE, PASTA) for critical systems and APIs.Design, implement, and oversee automated processes for securely updating application and code dependencies, proactively mitigating issues and ensuring timely vulnerability remediation.Integrate security checks into CI/CD pipelines (SAST, DAST, SCA, IaC), working with tools like Semgrep, Snyk, Trivy, and Burp Suite.Contribute to runtime security initiatives, such as container/Kubernetes hardening, RASP, and eBPF-based detection.Build and maintain a security issues dashboard to track remediation status and metrics.Provide real-time support in the event of cybersecurity incidents impacting applications or cloud infrastructure (exploited vuln, credential stuffing, web/API attacks).
Partner with the Cloud Security team on security automation tasks and monitoring improvements (e.g., Security Hub remediation automations, DLP monitoring).
Conduct proactive research on new threats, vulnerabilities, and attack techniques relevant to Rain's architecture.Collaborate with the GRC team to develop and deliver internal security awareness initiatives, phishing campaigns, and developer training (e.g., secure coding, API security).
Participate in the continuous improvement of AppSec maturity (e.g., aligning with OWASP SAMM, ISO 27001, or SOC 2 frameworks).
Required QualificationsFluent English, including strong verbal and written skills.Strong problem-solving and analytical mindset.Excellent communication skills to convey security risks to technical and non-technical stakeholders.3–5+ years of experience in application security, penetration testing roles, and/or secure code development, including work with QA teams.Hands-on experience with SAST, DAST, and SCA tools (e.g., Semgrep, Burp, Snyk).
Deep understanding of web, mobile, and API vulnerabilities (OWASP Top 10, API Top 10, MITRE CWE).
Proven expertise in performing code reviews or security assessments and writing clear reports.Proficiency in at least one backend language (e.g., Go, Python, Node.js) and understanding of React/React Native front-ends.Familiarity with secure architecture of microservices, event-driven systems, and REST APIs using OAuth2/OpenID Connect.Experience securing CI/CD pipelines and integrating AppSec tooling into SDLC.Solid knowledge of containerization and Kubernetes security fundamentals.Understanding of cloud security (preferably AWS), including IAM principles, cloud-native service configurations, and network segmentation.Comfortable with Agile development methodologies and working within cross-functional squads.Software supply chain security (e.g., SBOM, artifact signing).
Preferred QualificationsCertifications such as OSCP, OSWE, GWAPT, CPTE, or CSSLP.AWS, GCP, or Azure Security Specialty certification.Familiarity with bug bounty triage and vulnerability management platforms (e.g., DefectDojo).
Experience implementing RASP or eBPF runtime protection tools.Exposure to LLM/AI security considerations and secure code generation practices.Familiarity with logging and monitoring tools (e.g., CloudWatch, Datadog, Grafana).
Who We AreRain is filled with people with a deeply rooted passion for our mission, who embrace diversity throughout our global team, and grow personally and professionally.
We own what we do and let data guide our actions while working quickly and adapting to new challenges every day.
Rain is committed to Equal Employment Opportunity and does not discriminate based on race, religion, color, national origin, ethnicity, gender, sex (including pregnancy), protected veteran status, age, disability, sexual orientation, gender identity, gender expression, or any unlawful criterion existing under applicable federal, state, or local laws.
If you need assistance or accommodation due to a disability, you may contact us at ******.
We're not listing a separate location here; there is interest in candidates in locations including the Vitoria, Brazil Metropolitan Area.Referrals increase your chances of interviewing at Rain by 2x.
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