Senior App Security Engineer - Build Tools & PoCs

Cybersecurity Jobs; San Jose (CA); On-site; USD 140,000 - 210,000; Full time

Job summary

J2B Global LLC is seeking a Senior Application Security Engineer for a hands-on, contract role in San Jose, CA. The position focuses on finding, reproducing, and validating security issues across distributed systems and microservices, with an onsite schedule for five days a week.

With 8+ years of experience, you will build practical security tooling, perform deep source code reviews, and drive remediation into production-ready outcomes in collaboration with engineers and code owners.

Qualifications

• 8+ years of experience in software engineering or security engineering.
• Strong hands‑on programming and debugging in Java, C++, or Python.
• Experience with multiple programming languages preferred.
• Knowledge of application security, secure coding standards, and vulnerability remediation.

Responsibilities

• Develop security tools, testing utilities, vulnerability reproduction scripts, and automated validation frameworks.
• Assess architecture including trust boundaries, data flows, attack surfaces across distributed systems and microservices.
• Investigate scanner results, reproduce vulnerabilities, create PoCs, and separate true issues from false positives.
• Conduct detailed source code reviews to uncover security flaws and insecure coding practices.
• Review, test, and validate security patches including AI-generated and automated fixes.
• Build test harnesses and run unit, regression, and security tests to confirm remediation.
• Use threat modeling to identify architectural risks and recommend secure design practices.
• Evaluate vulnerabilities using CVE, CWE, OWASP Top 10 and remediation SLAs.
• Collaborate with engineers to implement fixes and support production deployment.
• Track vulnerabilities through lifecycle and contribute to secure SDLC improvements.

Skills

Java

C++

Python

Tools

SAST/DAST tools

PoCs

Job description

J2B Global LLC is seeking a Senior Application Security Engineer for a hands-on, contract role in San Jose, CA. The position focuses on finding, reproducing, and validating security issues across distributed systems and microservices, with an onsite schedule for five days a week.

With 8+ years of experience, you will build practical security tooling, perform deep source code reviews, and drive remediation into production-ready outcomes in collaboration with engineers and code owners.