Harmonic Security
Harmonic Security Limited (UK) and Harmonic Security Inc. (US)
Finds shadow AI and keeps sensitive data out of AI tools used by employees and agents, across browser, endpoint and MCP
Last checked October 15, 2026Quick facts: Harmonic Security is an AI compliance vendor founded in 2023 and headquartered in London, United Kingdom. The vendor publicly documents coverage for EU AI Act, HIPAA, SOC 2, and ISO 27001. Pricing is tiered. Profile last checked October 15, 2026; sources are cited at the bottom of this page.
About Harmonic Security
Harmonic Security sells software that shows security teams how employees and AI agents use generative AI tools and stops sensitive data from going into them. It was founded in 2023 (its About page dates the founding to August 2023) by CEO Alastair Paterson, the former chief executive of Digital Shadows, and CTO Bryan Woolgar-O'Neil. It launched in October 2023, jointly headquartered in London and San Francisco, and its privacy policy names Harmonic Security Limited in London and Harmonic Security Inc. in San Francisco. It says it has raised $76 million in total: a $7 million seed round led by Ten Eleven Ventures (October 2023), a $17.5 million Series A led by Next47 (October 2024) and a $50 million Series B led by Crosspoint Capital Partners, announced on October 14, 2026, when it reported more than 100 customers and more than 90 staff in the US and UK. We found no acquisition. The platform is sold as three packages. Explore uses a browser extension to find the AI tools in use and gives prompt-level visibility, usage intelligence, sensitive data detection and risk scores for each app; Harmonic says it covers more than 1,000 AI applications, including AI features inside SaaS tools. Guide adds an endpoint agent for desktop AI apps, IDEs and command-line tools such as Claude Code and Codex, inline coaching (block, warn or log), granular policies and webhook alerts for SIEM and SOAR tools. Command adds MCP client and server discovery, permissions on what agents may read, write and execute, and data protection inside agentic workflows; prompt injection detection is listed as coming soon. Its locally installed MCP Gateway, launched in October 2025, intercepts MCP traffic on Windows, macOS and Linux. Instead of pattern matching, Harmonic classifies prompts with its own small language models, which it says decide in under 200 milliseconds. **AI compliance coverage** Harmonic treats compliance as a by-product of governance. Its compliance page says it flags high-risk uses such as automated hiring screens and credit scoring "so you can apply the specific guardrails the EU AI Act and local laws require", keeps an audit trail of AI interactions, and blocks health and personal data from unapproved AI tools for HIPAA and GDPR. Documentation mapping its controls to specific regulations is available on request, as is EU hosting. For Harmonic itself, its trust center lists SOC 2 Type 2 and ISO/IEC 27001:2022, with a SOC 2 report available on request, and its site footer shows SOC 2 Type 2 and ISO 27001 badges. ISO/IEC 42001 and the NIST AI RMF also appear in the trust center's list, but the site shows no badge or certification claim for either. **Who it's for** Security and IT teams that want to let staff use ChatGPT, Claude, Copilot, Cursor and similar tools while keeping company data out of them. Harmonic has industry pages for technology, legal, insurance and healthcare, and its site quotes customers at Apax and Advisor360.
Frameworks supported
Regulations, voluntary standards and compliance programs Harmonic Security documents support for on their own materials. Chip shading reflects the strength of the claim, not an independent audit.
Regulation · EU · Phased — in force; high-risk rules deferred
Regulation · United States · active
Attestations held
Third-party security attestations and certifications Harmonic Security documents on their own materials. These are point-in-time auditor opinions, not regulatory compliance. Always request the current report or certificate directly from the vendor before relying on it.
Attestation · United States (AICPA)
Attestation · International (ISO)
Harmonic Security features
Capabilities Harmonic Security markets publicly. Inclusion means the feature is documented on the vendor's site — not that it's best-in-class. Last checked October 15, 2026.
Shadow AI Detection
Discovery of unsanctioned AI tools and model usage across an organization.
AI Discovery
Inventory of AI assets, models, prompts, and datasets across an enterprise environment.
Data Leakage Prevention
Inspection of LLM outputs to block PII, secrets, and regulated data from leaving the boundary.
Policy Enforcement
Mechanism for applying organizational and regulatory policies to AI usage at runtime.
Runtime Enforcement
Inline policy enforcement on AI inputs and outputs at request time.
Risk Scoring
Quantitative risk assessment for AI use cases, vendors, or model deployments.
Audit Logging
Tamper-evident logging of governance events (approvals, model changes, policy decisions) required by EU AI Act Article 12 and similar regulations.
Industries served
Integrations
Documented by Harmonic Security in public product materials.
- Okta
- Microsoft Entra ID
- Google Workspace
- OpenTelemetry
- AWS Marketplace
Harmonic Security pricing
Three packages, Explore, Guide and Command (marked most popular), are listed on Harmonic's pricing page without prices; the page offers a demo. AWS Marketplace lists "Harmonic Security - Explore" at $163.00 per user per year on a 12-month contract, with a 200-user minimum and private offers for custom quotes.
Pros and cons of Harmonic Security
Pros
- Three enforcement points in one product: a browser extension for web AI tools and AI features inside SaaS apps, an endpoint agent for desktop apps, IDEs and CLI tools such as Claude Code and Codex, and a local MCP gateway for agent traffic.
- Coaches rather than only blocks: each policy can block, warn or log, and Harmonic says most customers start in warn-and-log mode during rollout.
- Agent controls beyond chat: the Command package discovers MCP clients and servers and sets read, write and execute permissions for agents across connected MCP servers.
- A marketplace price gives buyers a reference point: AWS Marketplace lists the Explore package at $163 per user per year with a 200-user minimum.
- Privacy options for the workforce: employee names can be masked in the portal, departments can be excluded from reporting, and EU hosting is available on request.
Cons
- No prices on Harmonic's own site: the pricing page lists three packages and offers only a demo.
- EU AI Act and GDPR support is described in general terms; the documentation mapping its controls to regulations is available only on request.
- Prompt injection detection and blocking is listed on the pricing page as coming soon, so it is not yet a defense against prompt injection.
- ISO/IEC 42001 and the NIST AI RMF appear in its trust center's list, but the site shows no certification claim for either and its product pages don't describe support for them.
- Control depends on Harmonic's browser extension, endpoint agent or MCP gateway being installed; the API and OpenTelemetry feeds it ingests add visibility, not control.
- Young company: founded in August 2023, with more than 90 staff and more than 100 customers when it announced its Series B in October 2026.
Alternatives to Harmonic Security
Frequently asked
What is Harmonic Security?+
Harmonic Security is a London and San Francisco company, founded in 2023, that finds the AI tools employees and agents use and keeps sensitive data out of them. It works through a browser extension, an endpoint agent for desktop apps, IDEs and CLI tools, and a local MCP gateway for AI agents, and it coaches users by blocking, warning or logging.
How much does Harmonic Security cost?+
Harmonic doesn't publish prices on its own site; its Explore, Guide and Command packages are quoted after a demo. AWS Marketplace lists the Explore package at $163.00 per user per year on a 12-month contract, with a 200-user minimum.
Does Harmonic Security help with the EU AI Act and GDPR?+
Partly. Harmonic says it flags high-risk AI uses such as hiring screens and credit scoring so teams can apply EU AI Act guardrails, keeps an audit trail of AI interactions, and blocks personal and health data from unapproved AI tools. It offers documentation mapping its controls to regulations, and EU hosting, on request; ask to see that mapping before relying on it for an audit.
What are the alternatives to Harmonic Security?+
The closest alternatives in this directory are Prompt Security, Nightfall AI, WitnessAI, Knostic and Lasso Security, which also discover employee or agent use of AI and apply controls to it. Harmonic positions itself alongside SASE tools such as Zscaler and Netskope, which it says see the traffic but not what's inside the prompt, and alongside Microsoft Purview, which it says protects Microsoft AI while Harmonic protects everything else.
Sources
- Harmonic Security: Home (products, deployment, FAQ on EU AI Act, GDPR and EU hosting)
- Harmonic Security: Pricing and packages (Explore, Guide, Command; no prices)
- Harmonic Security: About (founders, August 2023 founding, seed and Series A timeline)
- Harmonic Security: Privacy policy (Harmonic Security Inc., San Francisco; Harmonic Security Limited, London)
- Harmonic Security: Why Harmonic (enforcement surfaces, small language models, 1,000+ AI apps)
- Harmonic Security: Explore (AI tool discovery, app risk scores, deployment)
- Harmonic Security: Command (agent permissions, governance at the MCP layer)
- Harmonic Security: MCP Gateway
- Harmonic Security: Compliance (EU AI Act, GDPR, HIPAA, audit trail)
- Harmonic Security Trust Center (SOC 2 Type 2, ISO/IEC 27001:2022, subprocessors)
- Harmonic Security: Product update, January 2025 (Okta, Google Workspace and Entra ID identity integrations)
- Harmonic Security: Harmonic Security launches MCP Gateway (October 15, 2025)
- Harmonic Security: Now available on AWS Marketplace (November 4, 2025)
- AWS Marketplace: Harmonic Security - Explore ($163 per user per year, 200-user minimum)
- Harmonic Security: Raises $17.5M Series A led by Next47 (October 2, 2024)
- Business Wire: Harmonic Security launches with $7M seed round led by Ten Eleven Ventures (October 2023)
- Business Wire: Harmonic Security raises $50 million Series B led by Crosspoint Capital Partners ($76M total; October 14, 2026)
- SiliconANGLE: Harmonic Security raises $50M to govern how employees use AI tools (October 14, 2026)
- SecurityWeek: Harmonic raises $17.5M to defend against AI data harvesting (October 2, 2024)
- Help Net Security: Harmonic Security raises $17.5 million (October 2, 2024)
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