Best AI Security markBest AI Security

Head to head · Checked against vendor sites, September 2026

Harmonic Security vs Prompt Security: which is better for shadow AI and employee AI use?

The verdict

Harmonic Security edges Prompt Security on our rubric (7.1 vs 6.6) thanks to published deployment through Intune, JAMF, Kandji or Group Policy and block, warn or log choices. Prompt Security, now part of SentinelOne, covers more ground, including homegrown AI apps, and is the natural choice for SentinelOne customers.

Harmonic Security

Best for data protection in everyday AI use

Read the Harmonic Security review

Prompt Security (SentinelOne)

Owner: SentinelOne (acquisition announced 5 August 2025)

Best for SentinelOne customers

Read the Prompt Security review

How do Harmonic Security and Prompt Security compare on each criterion?

Endpoint AI control score, editorial assessment 0-10. Edge is the higher score on each row.
CriterionWeightHarmonic SecurityPrompt SecurityEdge
Visibility22%77Tie
Why these scores

Harmonic Security: Finds AI tool use across browsers, desktop apps and CLI tools, including local tools on devices.

Prompt Security: Inventories AI tools and code assistants, including shadow AI, and maps agents and MCP servers.

Tool-call control20%76Harmonic Security
Why these scores

Harmonic Security: Governs at the MCP layer and tool surface, with permissions for what agents can read, write to and act on.

Prompt Security: Governs what agents and MCP servers can do; per-tool-call enforcement is not detailed.

Policy15%87Harmonic Security
Why these scores

Harmonic Security: Block in real time, warn the employee with context, or log silently; data classification by work intent.

Prompt Security: Prevents prompt injection and data leakage for tools such as GitHub Copilot, Cursor and Claude Code.

Identity and audit12%65Harmonic Security
Why these scores

Harmonic Security: Unified governance for humans and agents in Harmonic Command; per-action attribution not detailed.

Prompt Security: Agent vs human attribution not described on the pages we reviewed.

Footprint13%86Harmonic Security
Why these scores

Harmonic Security: Rolls out through Intune, JAMF, Kandji or Group Policy with no proxy redesign.

Prompt Security: Built into the SentinelOne Singularity Platform; the deployment method is not detailed.

Breadth8%68Prompt Security
Why these scores

Harmonic Security: Centered on data protection in AI use; browser, desktop, MCP and API surfaces.

Prompt Security: Employees, developers and homegrown AI apps from testing to runtime.

Maturity10%78Prompt Security
Why these scores

Harmonic Security: Publishes named packaging tiers (Explore, Guide, Command) but no prices.

Prompt Security: Backed by SentinelOne, which announced the acquisition on 5 August 2025; pricing not published.

Total100%7.16.6Harmonic Security

How we score

What problem do both solve?

Both start from the same question: which AI tools are employees and developers using, and what data is going into them. Both find unsanctioned shadow AI, cover coding assistants and extend to agents and MCP servers.

Where does Harmonic Security lead?

Deployment and policy. Harmonic states it rolls out through standard endpoint management tools without proxy changes, lets security teams choose between blocking, warning with context or logging silently, and sets MCP permissions for which systems agents can read, write to and act on. It also publishes its tier names, which Prompt Security does not.

Where does Prompt Security lead?

Breadth and backing. Prompt Security covers employees, developers and homegrown AI apps from pre-production testing to runtime, and it is built into the SentinelOne Singularity Platform. SentinelOne announced the acquisition on 5 August 2025. Its public page does not detail the deployment method.

Which should you choose?

Choose Harmonic Security if

  • Data leaving through AI tools is the main concern.
  • You want to coach users rather than only block.
  • You deploy through Intune, JAMF or Kandji.

Choose Prompt Security if

  • You run SentinelOne Singularity.
  • You also build AI apps that need testing and runtime protection.
  • You want developer code assistant protection in the same platform.

Frequently asked questions

Which is cheaper?

Neither publishes prices. Harmonic publishes tier names (Explore, Guide, Command). Ask both for quotes.

Do they cover AI agents?

Both extend to agents and MCP servers: Harmonic through Harmonic Command at the MCP layer, Prompt Security by mapping agents and MCP servers and finding shadow MCP servers.

Related

Sources