Sam Stewart joins Serval as Head of Security

Sam Stewart, founder of software supply chain security startup Ensignia, will lead security at Serval as its AI agents take on more of the enterprise's most sensitive work.

Sam has spent his career making sure the software companies depend on is built and shipped safely.

Now he's bringing that work to Serval, which has acquired Ensignia, the software supply chain security startup Sam founded, and named him head of security.

In the role, Sam will lead Serval's security function across detection and response, corporate security, application security, and infrastructure security. That includes the guardrails, permissions, and audit trails that govern how Serval's automation agents interact with customer systems.

"IT sits at the center of a company's most sensitive systems: employee access, credentials, endpoints, and the automations that touch all of them. If that layer isn't secure, nothing else matters," said Alex McLeod, co-founder and chief technology officer of Serval. "We built Serval on the premise that automation and security have to advance together."

Sam founded Ensignia to help organizations build trusted software by verifying the integrity of the code, dependencies, and build pipelines they ship. Before Ensignia, he built infrastructure security systems and teams at Brex, Cruise, and Culture Amp. Earlier in his career, he founded and sold Claiming.com.au.

The acquisition comes as Serval scales quickly to meet demand from large enterprise customers. The company raised a $75 million Series B led by Sequoia Capital in December 2025, valuing it at $1 billion just months after its Series A. Since launching in 2024, Serval has grown to over 100 employees and expanded from IT into HR, security, finance, legal, and other support functions. Companies including Fox, Live Nation, Notion, Legora, Clay, and Mercor run on Serval.

"IT teams want the speed AI promises, but they are not going to hand over their most sensitive systems until they trust it. That trust starts with security," Sam said. "I've spent years building teams and systems to ensure software gets shipped safely, and that's exactly the rigor Serval's customers need to trust AI with their most critical workflows."