Harmonic Security, a workforce AI security platform, has raised a US$50 million Series B funding round led by Crosspoint Capital Partners. The oversubscribed round included participation from existing investors and brings the company's total funding to US$76 million. The San Francisco and London-based company will use the new capital to accelerate engineering and go-to-market growth on both sides of the Atlantic.
Funding and Growth Plans
The Series B was led by Crosspoint Capital Partners, with existing investors also participating in the oversubscribed round. Harmonic did not disclose a valuation, but the financing lifts its total funding to US$76 million. The company now employs more than 90 people across the United States and the United Kingdom and has signed distribution partnerships with Climb and Distology.
Harmonic says its software is used by millions of employees at more than 100 companies, including some of the largest enterprises globally. SecurityBrief UK reported that Harmonic acquired around 100 customers in 2026 and reached its annual target in September. The new capital will support additional investment in engineering, sales, and marketing across both regions.
How the Platform Works
Harmonic's platform classifies every AI task, discovers why employees use it, and applies controls in real time. The company is the only platform that combines this task-level classification with real-time control across browser, desktop, and agentic workflows. Coverage now extends beyond browser-based AI monitoring to close gaps around personal account use, sensitive data exposure, and other risks.
The company credits its custom small language models for providing context into each AI interaction. These models read interactions in milliseconds and can distinguish between a developer referencing a schema and someone pasting live credentials. This contextual understanding helps security teams apply low-friction controls rather than blocking employee AI use entirely.
The same engine powers Harmonic's Usage Intelligence layer, which shows leaders which AI use cases create value and where to invest next. It also identifies employees who have found faster ways to work, helping organizations say yes to productive AI adoption. Harmonic supports ecosystem integrations with Cisco Cloud Control's Agent Builder through Model Context Protocol and with Claude's Compliance API for visibility into Anthropic-hosted deployments.
Market Momentum and Leadership
Harmonic Security is led by CEO and co-founder Alastair Paterson, who previously co-founded Digital Shadows and sold it to ReliaQuest for US$160 million in 2022. Paterson runs Harmonic alongside co-founder and Chief Technology Officer Bryan Woolgar-O'Neil, who held the same role at Digital Shadows. The company was established in October 2023 after consultations with more than 50 security leaders.
Competitors in the AI security space have pursued different strategies, with SentinelOne acquiring Prompt Security and Cato Networks agreeing to purchase Aim Security. Gartner projected that the security software sector, including AI security, could grow from US$15.6 billion in 2025 to US$37.6 billion by 2030, an annual growth rate of 18.5%. Harmonic's approach focuses on monitoring how employees use AI tools, and the company is expanding coverage of agents that access enterprise credentials.
Harmonic Security's Series B round positions it to scale its workforce AI security platform during a period of rapid enterprise AI adoption. Its contextual monitoring model aims to help security teams reduce risk while avoiding the slowdowns that often accompany new technology controls. With fresh capital, growing partnerships, and an expanded product scope, Harmonic plans to accelerate its momentum across the United States and the United Kingdom.