Is Onyx or Prompt Security better for AI endpoint control?

Neither is scored on this site. Onyx describes 3 of four product control types and Prompt Security 2 on the pages we read, and they differ on 8 recorded facts. Which fits depends on the AI tools people use, your devices, where the work happens and whether you block or guide; the finder checks those.

Which of the two decides on a tool call before it runs?

Onyx: Matches. Prompt Security: Not in our sources. Warn or ask: Onyx Matches, Prompt Security Not in our sources.

Do Onyx or Prompt Security publish prices?

Onyx: Not published. Prompt Security: Not published.

HEAD-TO-HEAD · FACTS ONLY

Onyx vs Prompt Security: AI endpoint control facts side by side

Short answer

Onyx describes 3 of the four product control types on the pages we read and Prompt Security describes 2; they differ on AI or MCP gateway. On decisions, Onyx decides on a tool call before it runs and Prompt Security does not describe tool-call decisions on the pages we read. We do not score either; the right choice depends on the AI tools people use, your devices, your current stack and whether you block or guide.

By The Device Desk · Endpoint AI Finder · Published 2026-10-11

Desk research from public vendor pages read on 27 September and 11 October 2026. Profiles follow our published method; we did not run the products.

Vendor pages read September and October 2026 · updated 2026-10-13

Where do their controls sit?

Filled or hatched marker: Onyx
Dashed teal ring: Prompt Security, described

DEV Filled marker: described on the product pages we read
DEV Hatched marker: partly described (another component, a narrower scope, or method not detailed)
DEV Dashed marker: not in our sources (it may exist; we did not find it)

The map shows where each product's own pages describe a control, or where your answers point. It is not a measure of how well a product works.

What are the facts, side by side?

Onyx Security and Prompt Security (SentinelOne), from each product's own pages. Differs is computed from recorded statuses, not wording.
Fact	Onyx	Prompt Security
Owner	None	SentinelOne (acquisition announced 5 August 2025; SentinelOne's blog of 3 September 2025 is titled SentinelOne Acquires Prompt Security)
Positioning	"The Secure AI Control Plane for the Agentic Era": inline inspection of prompts, tool calls and model responses across browser AI, coding assistants, desktop AI agents, cloud workloads and MCP servers. Based in Tel Aviv and New York.	Prompt Security, now part of SentinelOne, inventories AI tools and code assistants, including unsanctioned shadow AI, through two local sensors, a browser extension and a dedicated AI endpoint agent, and is built into the SentinelOne Singularity Platform.
How it reaches devices	Endpoint agents, browser extensions, APIs and gateways. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Two local sensors: a browser extension and a dedicated AI endpoint agent, managed from the SentinelOne Singularity Platform. Prompt Security argues that MDM or EDR integrations, which mostly run scripts periodically, are not enough. Source: Prompt Security blog: browser and endpoint sensors · Read 11 Oct 2026
On-device control	DescribedEndpoint agents cover coding assistants and desktop AI agents. Source: Onyx Security: AI security platform · Read 27 Sep 2026	DescribedA dedicated AI endpoint agent detects new AI agents, skills and connectors and applies runtime policies; it names GitHub Copilot, Cursor and Claude Code among the code assistants it inventories. Source: Prompt Security blog: browser and endpoint sensors · Read 11 Oct 2026
Browser extension	DescribedBrowser extensions cover browser AI. Source: Onyx Security: AI security platform · Read 27 Sep 2026	DescribedA browser extension inspects prompts, redacts sensitive data and discovers shadow AI. Source: Prompt Security blog: browser and endpoint sensors · Read 11 Oct 2026
Network or SSE proxy	Not in our sourcesNot described on the pages we read.	Not in our sourcesNot described on the pages we read.
AI or MCP gatewayDiffers	DescribedGateways and APIs inspect traffic inline. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sourcesNot described on the pages we read.
Names the coding agents it coversDiffers	PartlyCovers coding assistants; specific tools are not named on the pages we read. Source: Onyx Security: AI security platform · Read 27 Sep 2026	MatchesNames GitHub Copilot, Cursor and Claude Code. Source: SentinelOne: Prompt Security · Read 27 Sep 2026
Decides on a tool call before it runsDiffers	MatchesInspects every prompt, tool call and model response inline. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sources
Controls what goes into browser AI	MatchesCan mask data in browser AI as well as block it. Source: Onyx Security: AI security platform · Read 27 Sep 2026	MatchesThe browser extension inspects prompts and redacts sensitive data. Source: Prompt Security blog: browser and endpoint sensors · Read 11 Oct 2026
Rolls out through EDR or device management you runDiffers	Not in our sources	PartlyIts own agent and extension, managed in the SentinelOne console; it does not ride on other EDR or MDM tools. Source: Prompt Security blog: browser and endpoint sensors · Read 11 Oct 2026
Can warn or ask instead of only blockingDiffers	MatchesFive actions: alert, block, mask, steer or ask. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sources
Can block an agent, tool or actionDiffers	MatchesBlock is one of five actions. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sources
Has a watch-only or simulation modeDiffers	PartlyAlert is one of five actions; a simulation mode is not described. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sources
Records who or what took each actionDiffers	PartlyIntegrates with Okta, Entra and Splunk; separating a person from an agent is not described. Source: Onyx Security: AI security platform · Read 27 Sep 2026	Not in our sources
Also covers SaaS, cloud or homegrown AI	MatchesCloud workloads and MCP servers as well as devices. Source: Onyx Security: AI security platform · Read 27 Sep 2026	MatchesCovers homegrown AI apps from testing to runtime. Source: SentinelOne: Prompt Security · Read 27 Sep 2026
Has a public price or tiers (vendor site or marketplace)	Not in our sources	Not in our sources
Built into	None	Built into the SentinelOne Singularity Platform. Source: SentinelOne: Prompt Security · Read 27 Sep 2026
Works with	Lists CrowdStrike among its integrations. Source: Onyx Security: AI security platform · Read 27 Sep 2026	None in our sources
Price	Not published. Source: Onyx Security homepage · Read 27 Sep 2026	Not published. Source: SentinelOne: Prompt Security · Read 27 Sep 2026

Where do they differ?

AI or MCP gateway: Onyx describes it; Prompt Security is not in our sources.
Names the coding agents it covers: Onyx partly matches; Prompt Security matches.
Decides on a tool call before it runs: Onyx matches; Prompt Security is not in our sources.
Rolls out through EDR or device management you run: Onyx is not in our sources; Prompt Security partly matches.
Can warn or ask instead of only blocking: Onyx matches; Prompt Security is not in our sources.
Can block an agent, tool or action: Onyx matches; Prompt Security is not in our sources.
Has a watch-only or simulation mode: Onyx partly matches; Prompt Security is not in our sources.
Records who or what took each action: Onyx partly matches; Prompt Security is not in our sources.

Choose Onyx if

You want masking or steering rather than only allow or block
AI use spans the browser, desktop apps, coding tools and cloud workloads

Choose Prompt Security if

You already run SentinelOne Singularity
You need an inventory of AI tools and coding assistants first

Which limits should you check?

Onyx

Uses its own endpoint agents and browser extensions, so there is something new to roll out to devices.
No pricing published, and specific coding agents are not named on the pages we read.

Prompt Security

Two new local sensors to roll out, a browser extension and an endpoint agent, unless you already run SentinelOne.
Tool-call decisions, blocking, warning and activity records for agent actions are not described on the pages we read, and no pricing is published.

Line up Onyx and Prompt Security with others Run the finder