AI Defense Stack

LLM firewalls & guardrails

Prompt Security: AI firewall and usage control platform

Prompt Security is an AI firewall and usage control platform from SentinelOne. It is a commercial product offered as: Browser extension, API. Pricing model: not published.

  • Last reviewed
Visit Prompt Security (opens in a new tab)
Commercial Layer 6: Runtime guardrails

Best for

Security teams that already run SentinelOne and want AI usage controls and agent governance in the same console

Ownership

SentinelOne reported in a Form 8-K dated September 8, 2025 that its acquisition of Prompt Security was completed on September 5, 2025. Source, checked October 21, 2026: sec.gov (opens in a new tab)

Consider instead if

  • You want a standalone hosted guardrail API that your own application calls. See Lakera Guard.
  • You want an open-source library you can modify and run entirely yourself. See NeMo Guardrails.

What Prompt Security does

Prompt Security is a commercial AI security platform that SentinelOne acquired, completing the deal on September 5, 2025. The SentinelOne product page describes a real-time AI firewall that blocks adversarial prompts and scrubs sensitive outputs, redaction of sensitive data across more than 15,000 AI services, discovery of unsanctioned AI tools and shadow MCP servers, and least-privilege access for agents. A separate agentic security page names an MCP Gateway, a browser extension and API integrations, plus a searchable log of agent sessions. The product is built into the SentinelOne Singularity Platform. We found no public pricing, documentation site or source repository for the core product, so confirm packaging details with the vendor.

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
SentinelOne (Prompt Security) Source, checked October 21, 2026: sec.gov (opens in a new tab)
Status
Active Source, checked October 21, 2026: sentinelone.com (opens in a new tab)
Ownership
SentinelOne reported in a Form 8-K dated September 8, 2025 that its acquisition of Prompt Security was completed on September 5, 2025. Source, checked October 21, 2026: sec.gov (opens in a new tab)
Open source
No: closed source (proprietary) Source, checked October 21, 2026: prompt.security (opens in a new tab)
Latest release
Not documented in the sources we checked
Deployment
Browser extension, API Source, checked October 21, 2026: sentinelone.com (opens in a new tab)
Pricing model
Not published in the sources we checked Source, checked October 21, 2026: sentinelone.com (opens in a new tab)
Website
sentinelone.com Source, checked October 21, 2026: sentinelone.com (opens in a new tab)
Documentation
Not documented in the sources we checked
API reference
Not documented in the sources we checked
Quickstart
Not documented in the sources we checked
Security page
Not documented in the sources we checked
Attestations or disclosure
Not documented in the sources we checked

Capabilities

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

Integrations

Where Prompt Security 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 Prompt Security covers, with the role, how each applies and what it rests on
LayerRoleHow it appliesBased on
L6 Runtime Runtime guardrails Primary Screen what goes into and comes out of a model in live traffic, and limit abuse of the model endpoint. Follows its category, LLM firewalls & guardrails
L7 Agent access Agent and tool access Also covers Documents least-privilege access controls for agents. Governs what agents can access and which actions they can take, with least-privilege scope
L5 Data Data protection Also covers Documents redaction of sensitive data across AI services. Redacts sensitive data and enforces policies across more than 15,000 AI services

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 Prompt Security, with the capabilities each mapping rests on
RiskHow it appliesBased on
LLM01 Prompt Injection The AI firewall blocks adversarial prompts, and jailbreaks are listed among the risks covered. Blocks adversarial prompts with a real-time AI firewall; Addresses jailbreaks among the risks the platform covers
LLM02 Sensitive Information Disclosure Sensitive data is redacted and outputs are scrubbed under policy. Redacts sensitive data and enforces policies across more than 15,000 AI services
LLM06 Excessive Agency Agent access and actions are governed with least-privilege scope. Governs what agents can access and which actions they can take, with least-privilege scope

Not mapped in our analysis: LLM05, LLM07, LLM09, LLM10. 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 LLM firewalls & guardrails, ranked within the category by Coverage Score.

NVIDIA NeMo Guardrails

NVIDIA

Open sourceApache-2.0
  • Library
  • Self-hosted
  • API

Adds programmable input, dialog, retrieval, execution and output rails to LLM applications.

Best for: Teams that want to script rules for one LLM application in Python and run them in their own infrastructure

Coverage Score 76 out of 100
  • LLM01 Prompt Injection
  • LLM02 Sensitive Information Disclosure
  • LLM05 Improper Output Handling
  • LLM06 Excessive Agency

Reviewed

Portkey AI Gateway

Palo Alto Networks (Portkey)

Open sourceMIT Freemium Now Prisma AIRS AI Gateway
  • SaaS
  • Self-hosted
  • API

Routes LLM traffic through one gateway API and runs input and output guardrail checks on each request.

Best for: Teams that want a single gateway for several LLM providers with guardrail checks, available as open source or as a hosted service

Coverage Score 69 out of 100
  • LLM01 Prompt Injection
  • LLM02 Sensitive Information Disclosure
  • LLM05 Improper Output Handling
  • LLM09 Misinformation

Reviewed

Kong AI Gateway

Kong

Open sourceApache-2.0
  • Self-hosted
  • SaaS
  • API

Routes LLM traffic through Kong with prompt guards, PII sanitization, spend limits and observability.

Best for: Teams that already run Kong as an API gateway and want LLM routing and prompt controls on the same data plane

Coverage Score 65 out of 100
  • LLM01 Prompt Injection
  • LLM02 Sensitive Information Disclosure
  • LLM10 Unbounded Consumption

Reviewed

Prompt Security FAQ

Is Prompt Security open source?

No. The platform is commercial. The vendor site links public repositories for separate tools such as ps-fuzz, but we found no public source for the platform itself.

Who owns Prompt Security?

SentinelOne reported in a Form 8-K that it completed its acquisition of Prompt Security on September 5, 2025, and the product is now presented as part of the SentinelOne Singularity Platform.

Does Prompt Security publish prices?

No. The product page states no prices and directs readers to book a demo.

Key facts you can cite

We have no commercial relationship with SentinelOne (Prompt 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.