Harmonic Security collected $50M in an oversubscribed Series B to expand software that inspects employee AI use before anything reaches a model.
The London and US-based company, which previously raised a $17.5M Series A led by Next47 in October 2024, drew Crosspoint Capital Partners as lead for the new round, backed by its earlier investors.
The product sits in the path of the prompt. When an employee pastes something sensitive, such as a live credential, into a chat window, a purpose-built small language model reads the exchange in context and issues a verdict in milliseconds, before the target tool ever processes it. Coverage started inside the browser and now reaches desktop AI applications and agentic workflows, where personal-account sign-ins tend to originate.
Chief executive Alastair Paterson says every board he speaks with now asks two questions at once: whether AI is producing value, and how to contain the risk of using it. Harmonic’s response is a Usage Intelligence layer running on the same models, giving leaders a view of which AI tools are actually in use.
The company is also integrating with incumbent enterprise tooling. Cisco lists Harmonic among ecosystem integrations for its Agent Builder, connected over Model Context Protocol, and a second link pulls Anthropic Claude activity logs into Harmonic’s dashboard.
More than 100 companies are customers, covering millions of employees, and headcount has passed 90 across the US and UK. Climb Global Solutions and Distology handle distribution.
