Harmonic Security Raises $50 Million Series B, Enabling Safe AI Adoption for Millions More Employees

Harmonic Security, which describes itself as a workforce AI security platform, announced a $50 million Series B funding round led by Crosspoint Capital Partners, with participation from existing investors. The company said the round was oversubscribed and brings its total funding to $76 million. Harmonic will use the capital to expand engineering and go-to-market operations on both sides of the Atlantic. The company, headquartered in San Francisco and London, has grown to more than 90 people across the United States and United Kingdom.

According to the company, Harmonic protects and enables AI use for millions of employees at more than 100 companies, including some of the largest enterprises globally. It also signed new distribution partnerships with Climb and Distology. Harmonic says its platform classifies every AI task, identifies why it is being used, and controls it in real time. Over the past 12 months, the company extended beyond browser-based AI monitoring to cover desktop AI tools and agentic workflows, a coverage expansion it says addresses the points where personal-account use and sensitive data exposure typically begin.

The company's small language models analyze each AI interaction in context, which Harmonic says allows it to distinguish, for example, a developer referencing a database schema from an employee pasting live credentials. The same engine powers the company's Usage Intelligence layer, which is designed to show leaders which AI use cases create value and where to invest, rather than only where to restrict use. Harmonic has also been named among ecosystem integrations for Cisco Cloud Control's new Agent Builder, announced at Cisco Live, connecting via Model Context Protocol. Separately, it built an integration with Anthropic's Claude Compliance API, giving security teams visibility into Claude Platform activity logs and, for Claude Enterprise customers, conversation content across Anthropic-hosted deployments.

CEO and co-founder Alastair Paterson said that boards increasingly ask how to reduce AI-use risk while capturing value, and that most vendors address only the first question. Zach Sivertson, Managing Director at Crosspoint Capital Partners, said security has often slowed technology adoption and that Harmonic provides leaders with the visibility to accelerate AI adoption within appropriate guardrails. Paterson said the round will allow the company to scale faster and respond to shifts in the AI landscape.