Sr. Staff AI Security Engineer

📋 Job Overview

Innovate with purpose

At BILL, we believe in empowering the businesses that drive our economy. By replacing outdated financial processes with innovative tools, we help businesses—from startups to established brands—make smarter decisions and gain control of their operations. And we don’t stop there: we’re creating the future of financial automation so businesses can spend more time on what matters.

Working here means you become part of a vision-driven team that’s ready to tackle challenges and build cutting-edge solutions. We value purpose, drive, and curiosity—and we thrive in a fast-paced, ever-changing environment. We're remote-first, with office spaces in San Jose, CA and Draper, UT — and opportunities to connect in person when it counts. BILLders collaborate to deliver real impact for businesses that need more time in their busy weeks.

🏢 About BILL

BILL builds high performing teams and we seek to hire the best talent for every role. We're committed to building a workplace that fosters inclusion and diverse perspectives, valuing each person’s unique skills and experiences. We’d love to hear from you—you might be just what we’re looking for, whether in this role or another.

🎯 The Role

We are looking to hire a Sr. Staff AI Security Engineer to lead the secure deployment and operation of AI and ML systems across the company. This role moves beyond traditional perimeter security to address the unique vulnerabilities of Large Language Models (LLMs) and automated orchestration layers. Your mission: provide a secure foundation—gateways, orchestration layers, and tool ecosystems—that enables developers to innovate at pace while maintaining a robust security posture.

You'll partner with platform, engineering and IT teams as a builder and enabler rather than a gatekeeper, embedding security into the AI development lifecycle by default and shaping how BILL navigates the AI threat landscape.

✅ Key Responsibilities

• Design, build, and operate secure AI gateways and policy orchestration layers spanning multiple AI models and service providers
• Configure end point settings for AI tools in collaboration with IT end point management solutions.
• Stand up and lead a formal AI red-teaming practice covering prompt injection, jailbreaking, model extraction, and emerging attack vectors
• Identify and mitigate AI-specific threats across input manipulation, supply chain (model weights, datasets, third-party AI libraries), data privacy (training data leakage, PII disclosure), and model integrity (poisoning, unauthorized fine-tuning)
• Automate security checks and guardrails to enable rapid development cycles without sacrificing security posture
• Apply and operationalize the OWASP LLM Top 10 framework to categorize and mitigate risk
• Own the AI security roadmap and advise senior leadership on AI risks and safe adoption
• Embed with platform teams as a partner, fostering a collaborative security culture
• Mentor fellow engineers on AI security best practices
• Document and report vulnerabilities with clear remediation guidance and technical direction

📌 Required Qualifications

• A proven track record of building and scaling security systems in high-growth environments
• High proficiency in Python or Go to build, automate, and scale security tooling
• Deep understanding of LLM-specific attack vectors: prompt injection and jailbreaking
• Deep understanding and applied experience with the OWASP LLM Top 10 framework
• Experience designing secure API gateways, orchestration layers, and scalable security infrastructure using infrastructure as code
• Experience standing up red-teaming or adversarial testing programs
• A strong grasp of AI/ML fundamentals, including model supply chain and data privacy risks
• A builder mentality and passion for the AI space—you enable development through secure architecture rather than blocking it
• The ability to influence senior leadership and mentor engineers across the organization
• A background in Computer Science, Cybersecurity, or a related technical field

🎁 Benefits

• 100% paid employee health, dental, and vision plans (choose HMO, PPO, or HDHP)
• HSA & FSA accounts
• Life Insurance, Long & Short-term disability coverage
• Employee Assistance Program (EAP)
• 11+ Observed holidays and wellness days and flexible time off
• Employee Stock Purchase Program with employee discounts
• Wellness & Fitness initiatives
• Employee recognition and referral programs
• And much more

🛂 Visa & Eligibility

Please note that this position is not eligible for visa sponsorship. Applicants must have authorization to work in the United States without requiring visa sponsorship now or in the future.