AI Defense Stack

GenAI data-leak prevention & privacy

Harmonic Security: workforce AI usage and data protection service

Harmonic is a workforce AI usage and data protection service from Harmonic Security. It is a commercial product offered as: Browser extension. Pricing model: not published.

  • Last reviewed
Visit Harmonic (opens in a new tab) Documentation (opens in a new tab)
Commercial Layer 5: Data protection

Best for

  • Security teams that want to see which AI tools employees use and coach or block sensitive data in the browser and on the endpoint
  • Engineering organizations that want sensitive data kept out of prompts and tool calls made by coding agents on developer machines

Consider instead if

  • You want data loss prevention that also covers SaaS apps and developer APIs, not only employee AI use. See Nightfall.
  • You cannot install an extension or agent on every device and want visibility at the network level instead. See WitnessAI.

What Harmonic does

Harmonic Security governs what employees and their AI agents send to AI tools, and it does so from the device. A browser extension covers web AI apps; a Protect Agent on the workstation reaches desktop apps and, since a September 2026 release, the hooks of coding agents such as Claude Code, Codex and Cursor; a local MCP gateway screens tool calls. That device-side design is the main contrast with WitnessAI, which watches traffic at the network level with no extension or endpoint client. Device agents see more context per user but must be rolled out through Intune, Jamf, Kandji or Group Policy, and an unmanaged laptop is outside their reach. The release notes we read mention uploaded files for one data type only, security incident reports, and the pricing page lists three packages without prices.

This summary is our own wording of the sourced facts on this page.

Key facts

Each value links to the page that states it, with the date we checked it.

Vendor
Harmonic Security Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Status
Active Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Open source
No: closed source (proprietary) Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Latest release
October 21, 2026 Source, checked October 21, 2026: docs.harmonicsecurity.app (opens in a new tab)
Deployment
Browser extension Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Pricing model
Not published in the sources we checked Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Website
harmonic.security Source, checked October 21, 2026: harmonic.security (opens in a new tab)
Documentation
docs.harmonicsecurity.app Source, checked October 21, 2026: docs.harmonicsecurity.app (opens in a new tab)
API reference
Not documented in the sources we checked
Quickstart
docs.harmonicsecurity.app Source, checked October 21, 2026: docs.harmonicsecurity.app (opens in a new tab)
Security page
trust.harmonic.security Source, checked October 21, 2026: trust.harmonic.security (opens in a new tab)
Attestations or disclosure
ISO/IEC 27001:2022; SOC 2 Type 2; ISO/IEC 42001:2023 Source, checked October 21, 2026: trust.harmonic.security (opens in a new tab)

Capabilities

As documented by the vendor or project. The tag is our label from a controlled vocabulary.

Integrations

Where Harmonic fits in our AI security layers

Our analysis

Our editorial model, not a standard. The primary layer follows the category, except for tools whose main documented job is detection and response; other layers rest on a capability the sources document. How the model works.

AI security layers that Harmonic covers, with the role, how each applies and what it rests on
LayerRoleHow it appliesBased on
L5 Data Data protection Primary Keep sensitive data out of prompts, uploads, retrieval and training data, or remove and tokenize it first. Follows its category, GenAI data-leak prevention & privacy
L2 Discovery Discovery and posture Also covers Documents a map of the AI tools that staff use, through shadow AI discovery. Maps the AI tools a workforce actually uses, including AI features embedded in SaaS tools
L8 Monitoring Monitoring and response Also covers Documents invocation logs of each MCP tool call, with parameters, responses and the user behind it. Keeps invocation logs of each MCP tool call, including parameters and responses, with user-level attribution

OWASP LLM Top 10 mapping

Our analysis

The risk list is OWASP's (Top 10 for LLM Applications, 2025). The mapping is our analysis, and each row rests on a capability the sources document.

OWASP LLM risks mapped to Harmonic, with the capabilities each mapping rests on
RiskHow it appliesBased on
LLM02 Sensitive Information Disclosure Detects sensitive data in prompts to AI tools and coaches, warns or blocks before it is shared. Detects sensitive data when an employee tries to share it with an AI tool and intercepts the prompt; Applies controls inside the browser through an extension for Chrome, Edge, Firefox and Safari; Sets enforcement by data type, application and role, from silent logging to warnings, coaching and blocking; Monitors or blocks sensitive data in prompts and tool calls of AI coding agents such as Claude Code, OpenAI Codex and Cursor; Local MCP gateway allows or blocks MCP servers and individual tools and checks tool calls for PII, secrets and credentials
LLM06 Excessive Agency The local MCP gateway allows or blocks MCP servers and single tools, which limits what an agent can do. Sets enforcement by data type, application and role, from silent logging to warnings, coaching and blocking; Local MCP gateway allows or blocks MCP servers and individual tools and checks tool calls for PII, secrets and credentials

Not mapped in our analysis: LLM07, LLM08. These are risks we expect tools in this category to cover; the sources we checked do not document a matching capability.

Alternatives and related tools

More in GenAI data-leak prevention & privacy, ranked within the category by Coverage Score.

Protecto

Protecto

Commercial
  • SaaS
  • On-prem
  • API

Detects sensitive data and tokenizes or masks it before it reaches LLMs, RAG pipelines and agents.

Best for: Teams that want an API that tokenizes or masks sensitive data before it reaches LLMs and RAG pipelines and restores it afterwards

Coverage Score 70 out of 100
  • LLM02 Sensitive Information Disclosure
  • LLM08 Vector and Embedding Weaknesses

Reviewed

Presidio

Data Privacy Stack

Open sourceMIT
  • Library
  • Self-hosted

Finds and masks personal data in text, images and structured data, and you run it yourself.

Best for: Engineering teams that want a free, self-hosted library to detect and anonymize PII before text reaches a model or a log

Coverage Score 67 out of 100
  • LLM02 Sensitive Information Disclosure

Reviewed

Limina (Private AI)

Limina

Commercial Freemium Now Limina
  • Self-hosted
  • On-prem
  • API

Detects PII, PHI and PCI in text, files, images and audio in a container you run in your own environment.

Best for: Teams that need PII, PHI and PCI de-identification of text, files and audio that runs inside their own VPC or on-premises

Coverage Score 64 out of 100
  • LLM02 Sensitive Information Disclosure

Reviewed

Harmonic FAQ

Is Harmonic Security open source?

No. Harmonic is a commercial service, and we found no public source repository for the product.

How is Harmonic deployed?

The vendor pages describe a browser extension that is installed through MDM tools such as Intune, Jamf and Kandji, with Group Policy also named, plus endpoint coverage in Harmonic Guide.

What does Harmonic cost?

The pricing page names Explore, Guide and Command packages with a Book a demo button and shows no prices, so pricing is not published.

Does Harmonic cover AI coding agents?

Yes, on managed devices. A September 25, 2026 release made sensitive data controls generally available for coding agents such as Claude Code, OpenAI Codex and Cursor, using each agent's hooks through the Harmonic Protect Agent; it monitors or blocks prompts and tool calls but not uploaded files. A local MCP gateway also screens MCP tool calls.

Key facts you can cite

We have no commercial relationship with Harmonic Security.

Sources & last reviewed

Last reviewed . We compile from the vendors' own public pages and repositories and we do not run the products. Source links open in a new tab. Found a mistake? Report a correction.