Harmonic Security, a San Francisco-based cybersecurity company focused on enterprise AI security, announced a $50 million Series B funding round on October 14, 2026. The round was led by Crosspoint Capital Partners, with participation from existing investors, bringing the company’s total funding to $76 million.
Founded in 2023 by CEO Alastair Paterson and CTO Bryan Woolgar-O’Neil, Harmonic Security develops software that helps enterprises monitor and control employees’ use of artificial intelligence tools while protecting sensitive business information. Both founders previously worked together at Digital Shadows, a cybersecurity company acquired by ReliaQuest in 2022.
Harmonic Security’s platform provides visibility into how employees interact with AI applications and enables organizations to apply security controls based on the context of those interactions. Its capabilities cover browser-based AI services, desktop AI applications and agentic workflows.
The platform uses specialized small language models to classify sensitive information and analyze how AI tools are being used. This approach helps security teams identify potential data exposure, understand workplace AI activity and apply controls without unnecessarily restricting employee access to AI applications.
According to the company, its platform serves millions of employees across more than 100 enterprises. Harmonic Security has also expanded its workforce to more than 90 employees across the United States and the United Kingdom.
The company plans to use the Series B proceeds to expand its engineering and go-to-market teams in both countries. It has also established distribution partnerships with Climb and Distology to support its commercial expansion.
Before this round, Harmonic Security raised $17.5 million in Series A funding led by Next47 in October 2024. Its earlier $7 million seed round, announced in October 2023, was led by Ten Eleven Ventures.
