Harmonic Security

Harmonic Security is a data-protection platform built for generative AI. It uses purpose-built language models to classify sensitive data in real time -- 'zero-touch' protection without heavy rule-writing -- and detects thousands of AI tools to surface shadow-AI usage. Founded in 2023 by a team with Digital Shadows heritage and backed by roughly $26M (Series A led by Next47), it is an independent, focused vendor modernizing DLP for the AI era.

Harmonic Security reimagines data loss prevention for the generative-AI era. Traditional DLP relies on brittle rules and regex that struggle with the free-form, contextual data flowing into AI tools. Harmonic instead trains its own language models on realistic sensitive-data examples so it can classify many types of sensitive information in milliseconds, aiming for high accuracy with minimal configuration -- what it markets as 'zero-touch' data protection. A second pillar is shadow-AI visibility. Harmonic can detect thousands of AI tools -- SaaS apps and AI-enabled web apps -- so security teams can see where employees are sending data and reduce the hidden overhead of ungoverned AI usage. Together, the classification and discovery capabilities help enterprises let employees use AI productively while preventing sensitive data from leaking into public models and tools. Harmonic was founded in 2023 (its team includes veterans of the threat-intelligence company Digital Shadows) and operates from San Francisco and the UK. It is independent and venture-backed: it raised a $7M seed led by Ten Eleven Ventures in 2023 and a $17.5M Series A led by Next47 in October 2024, for roughly $26M in total disclosed funding. Note that a different company, Prompt Security, was acquired by SentinelOne in 2025 -- Harmonic itself remains independent as of August 2026.