Sr. AI Security Engineer

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 By replacing outdated financial processes with innovative tools, we help businesses—from startups to established brands—make smarter decisions and gain control of their operations.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.

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.

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.

Design and implement secure gateways that act as controlled entry points for AI requests, ensuring all interactions are authenticated and logged. Build orchestration layers that enforce security policies (rate limiting, content filtering) across multiple AI models and providers. Integrate security controls into developer tool ecosystems so security is baked in by default—highly available, scalable via infrastructure as code, and never a performance bottleneck for production AI applications.

Own and stand up a formal AI red‑teaming practice to identify vulnerabilities before they reach production. Research and simulate advanced attack vectors including prompt injection, jail breaking, adversarial suffixes, model extraction, model poisoning, training data leakage, and AI supply chain compromise. Systematically document findings and deliver clear remediation paths to engineering teams.

Own the long‑term AI security roadmap, aligning technical goals with BILL's business mission. Act as the primary subject matter expert advising senior leadership on AI risk. Mentor engineers across the organization to raise BILL's collective security IQ.

• 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, jail breaking, 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…