CISO Tribune

Vendor comparison · 2 companies

Harmonic Security vs Prompt Security

Harmonic Security sells AI Governance and Control (AIGC), a control layer that secures and enables the AI-First workforce. Prompt Security offers protection for both employee use of AI tools and the apps an organization builds. CISO Tribune files both under Workforce AI usage security and AI model and agent security. This page sets the two records side by side: what each sells, where it is based, who owns and funds it, the customers it names and its recent news, each fact numbered to its source.

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  • Harmonic Security
  • Prompt Security
Harmonic Security vs Prompt Security: Products, Customers and Funding Compared
Harmonic SecurityHarmonic Security sells AI Governance and Control (AIGC), a control layer that secures and enables the AI-First workforce.harmonic.securityPrompt SecurityPrompt Security offers protection for both employee use of AI tools and the apps an organization builds.prompt.security
What it sells
  • Harmonic Command[3]Gives security teams visibility into how employees and agents use AI, plus controls for using the tools safely.
  • MCP Gateway[2][3][4][6]A local gateway that extends Harmonic coverage to MCP activity.
  • Harmonic Endpoint Agent[6]Identifies native AI apps, IDEs, CLI tools, locally hosted models and inference API calls on employee devices.
  • Harmonic Usage Intelligence[8]Groups prompts, files, responses, and supported agent actions into tasks and use cases.
  • Prompt Fuzzer[4]An open source tool for AI vulnerability assessment.
Categories
Headquarters
Not stated on its pagesNot stated on its pages
Founded
Not stated on its pages2023[1]
Ownership and funding
Privately heldOwned by SentinelOne since 2025[3][7][8][10]
Named customers
Not stated on its pagesNot stated on its pages
Recent news
Not stated on its pagesNot stated on its pages
G2 and Gartner Peer Insights
  • G2: Not stated on its pages
  • Gartner Peer Insights: Not stated on its pages
  • G2: listed, seen November 10, 2026[10]
  • Gartner Peer Insights: Not stated on its pages
Who it fits
Not written yetNot written yet
Last verified
November 3, 2026September 27, 2026

Where they overlap

  • Harmonic Security and Prompt Security are both filed under Workforce AI usage security and AI model and agent security.

Where they differ, field by field

  • Harmonic Security's primary category is Workforce AI usage security; Prompt Security's is AI firewalls and guardrails.
  • Harmonic Security is also filed under Data loss prevention and AI governance.
  • Harmonic Security lists Harmonic Command, MCP Gateway, Harmonic Endpoint Agent and Harmonic Usage Intelligence. Prompt Security lists Prompt Fuzzer.
  • Prompt Security was founded in 2023.
  • Harmonic Security is privately held. Prompt Security is owned by SentinelOne, since 2025.

What it sells: Harmonic Security

What Harmonic Command does[3]
Harmonic Command covers workforce AI use across supported browsers, desktop applications, command-line tools, AI APIs, and agentic workflows that use MCP. Harmonic Command intercepts the action and guides the user or agent toward a safer path.
What MCP Gateway does[2][3][4][6]
Supported OpenTelemetry sources and the local MCP Gateway extend Harmonic coverage to additional native, command-line, and MCP activity. The Harmonic MCP Gateway pairs with the Endpoint Agent and applies to agentic workflows. The MCP Gateway runs on Windows, macOS, and Linux.
What Harmonic Endpoint Agent does[6]
The Harmonic Endpoint Agent detects Claude Desktop, Claude Code, Claude Cowork and OpenAI Codex on macOS and Windows. The Endpoint Agent identifies locally hosted models such as Ollama on employee devices and ties that activity to the process and user behind it. Harmonic identifies connections to inference endpoints like OpenAI, Anthropic, Bedrock and Azure AI Foundry.

What it sells: Prompt Security

What Prompt Fuzzer does[4]
Prompt Fuzzer is listed under AI Security Tools on the Prompt Security site. The site describes it as an open source tool for AI vulnerability assessment.

Questions about Harmonic Security and Prompt Security

What do Harmonic Security and Prompt Security sell?
Harmonic Security sells Harmonic Command, MCP Gateway, Harmonic Endpoint Agent and Harmonic Usage Intelligence. Prompt Security sells Prompt Fuzzer.
Are Harmonic Security and Prompt Security in the same category?
They share Workforce AI usage security and AI model and agent security. Harmonic Security's primary category is Workforce AI usage security and Prompt Security's is AI firewalls and guardrails.
When were Harmonic Security and Prompt Security founded?
Prompt Security was founded in 2023.
Who owns Harmonic Security and Prompt Security?
Harmonic Security is privately held. Prompt Security is owned by SentinelOne, since 2025.

About Harmonic Security

Harmonic Security sells AI Governance and Control (AIGC), a control layer that secures and enables the AI-First workforce. Harmonic Security describes a platform that classifies every AI task, discovers why it is used, and controls it in real time. Harmonic Command covers workforce AI use across supported browsers, desktop applications, command-line tools, AI APIs, and agentic workflows that use MCP. Harmonic Command coverage includes ChatGPT, Claude, Copilot, Gemini, Cursor, and more than 1,000 web AI tools.[1][2][3]

Harmonic Command gives security teams visibility into how employees and agents use AI, plus controls for using the tools safely. Supported OpenTelemetry sources and the local MCP Gateway extend Harmonic coverage to additional native, command-line, and MCP activity. The Harmonic MCP Gateway pairs with the Endpoint Agent and applies to agentic workflows. The MCP Gateway runs on Windows, macOS, and Linux.[2][3][4][6]

The Harmonic Endpoint Agent identifies every native AI app, AI-first IDE, CLI tool, locally hosted model and direct inference API call running on employee devices. The Harmonic Endpoint Agent detects Claude Desktop, Claude Code, Claude Cowork and OpenAI Codex on macOS and Windows. Harmonic identifies connections to inference endpoints like OpenAI, Anthropic, Bedrock and Azure AI Foundry, and ties each connection back to the process and user that initiated it. The Endpoint Agent identifies locally hosted models such as Ollama on employee devices and ties that activity to the process and user behind it.[6]

Harmonic secures AI use in the browser with real-time visibility and control over how employees use AI tools. Harmonic identifies the specific account type and subscription plan in use. The Harmonic browser extension finds AI features running inside web apps, such as Magic Write in Canva. Harmonic can warn users as they are about to paste sensitive data, ask for a business justification, or steer them from an unsafe free tool to a sanctioned alternative. The Harmonic browser extension supports Chrome, Edge, Firefox and Safari, plus other Chromium browsers including Arc, Brave, Vivaldi, Island and Genspark.[7]

Harmonic Usage Intelligence groups prompts, files, responses, and supported agent actions into coherent tasks and organization-specific use cases, with views by department, employee, application, approval status, and time. Harmonic builds an inventory of the AI apps a workforce uses, who uses them and for what work. Harmonic records which tools are approved, how policy was applied, what was coached or blocked, and where sensitive data was exposed. Harmonic offers configurable retention, role-based access, employee masking and EU or US hosting. Harmonic does not train on customer data.[5][8][9]

Harmonic uses purpose-built small language models that read the whole prompt or file and interpret the nuance of natural language. Harmonic lets customers enforce enterprise accounts where data is ring-fenced, or restrict uploading corporate context into personal accounts. Harmonic can prevent the upload of protected health information and personally identifiable information to non-compliant models. Harmonic Security says it works with health systems, hospitals, payers and life sciences companies. Harmonic Security says it works with insurance carriers, brokers, MGAs and reinsurers. Harmonic can be deployed through Intune, Jamf, Kandji, or Group Policy.[1][2][3][4][5][8][10][11][12][13]

Harmonic Security on the record

Sources

Harmonic Security full record

  1. [1]Harmonic Security | AI Security for the WorkforceHarmonic Security · undated page, accessed November 3, 2026 · Tier A
  2. [2]Harmonic Security Raises $50 Million Series B Enabling Safe AI Adoption for Millions More EmployeesBusiness Wire · businesswire.com · published October 14, 2026 · Tier A
  3. [3]Harmonic Command: AI Governance & Usage Intelligence Platform | Harmonic SecurityHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  4. [4]Harmonic Explore: AI Usage Visibility & Shadow AI Discovery | Harmonic SecurityHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  5. [5]Harmonic Guide: Real-Time AI Policy Enforcement & Inline Controls | Harmonic SecurityHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  6. [6]Endpoint AI Security & ControlHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  7. [7]Browser-Based GenAI SecurityHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  8. [8]AI Usage IntelligenceHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  9. [9]AI Usage Governance: Enterprise AI Policy & ControlHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  10. [10]DLP for Generative AIHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  11. [11]GenAI Compliance for Regulated IndustriesHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  12. [12]AI Security for HealthcareHarmonic Security · undated page, accessed November 10, 2026 · Tier A
  13. [13]AI Security for InsuranceHarmonic Security · undated page, accessed November 10, 2026 · Tier A

Prompt Security full record

  1. [1]Prompt security partners with f5 to secure genai applications with a firewall for ai 302131373Prompt Security via PR Newswire · prnewswire.com · published April 30, 2024 · Tier A
  2. [2]Securing ai promptSentinelOne · sentinelone.com · undated page, accessed September 27, 2026 · Tier A
  3. [3]Sentinelone completes acquisition of prompt securitySentinelOne via The Globe and Mail · theglobeandmail.com · published September 5, 2025 · Tier A
  4. [4]Prompt Security | From SentinelOnePrompt Security · undated page, accessed October 27, 2026 · Tier A
  5. [5]AI Security | AI Glossary | Prompt SecurityPrompt Security · undated page, accessed October 27, 2026 · Tier A
  6. [6]ClawSec: A Security Skill Suite for OpenClaw AgentsPrompt Security · undated page, accessed October 27, 2026 · Tier A
  7. [7]AI Security Startups Map — Agentic AI Vendors by CategoryPrompt Security · undated page, accessed October 27, 2026 · Tier A
  8. [8]About this Map & Methodology — AI Security Startups MapPrompt Security · undated page, accessed October 27, 2026 · Tier A
  9. [9]OneClaw DashboardPrompt Security · undated page, accessed November 10, 2026 · Tier A
  10. [10]Prompt Security Pros and Cons | User Likes & DislikesG2 · undated page, accessed November 10, 2026 · Tier C

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