Comparison · 2026
Prompt Security · SentinelOne
Harmonic Security
Prompt Security vs Harmonic Security (2026)
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À propos de ce comparatif
Prompt Security and Harmonic Security often land in the same evaluation. Prompt Security spans application-side AI security and employee controls, now sold through SentinelOne; Harmonic governs AI at the point of use. This page compares the two on public, verifiable facts, then adds Aona in a third column and gives a verdict on the employee AI use criteria: hard block with no user override, layout-preserving file redaction, a 30-day self-serve trial, and seven hosting regions.
Aona AI publishes this page and appears in the third column. Every competitor claim is drawn from each company's own materials and reputable public sources, stated as the mechanism the vendor documents, and re-verified on 17 September 2026.
The verdict answers one buyer question, employee use of third-party AI tools, and names what each vendor is for. Capabilities and ownership change, so confirm the current details with each vendor before you decide, and test Aona on your own devices through its 30-day self-serve trial.
Prompt Security vs Harmonic Security vs Aona, side by side
The dimensions that decide an employee AI security evaluation. Competitor cells state the mechanism each vendor documents; the Aona column states the shipped Aona fact.
| Dimension | Aona | Prompt Security | Harmonic Security |
|---|---|---|---|
| Primary positioning | Workforce AI Security: employee use of AI tools on managed devices, with hard-block DLP for prompts and files. | Broad GenAI security platform spanning employees, homegrown AI apps, AI code assistants, and agentic AI; built into SentinelOne's Singularity platform. | AI data protection and governance focused on what employees and agents send to AI tools. |
| Shadow AI discovery | Per-user discovery across a catalogue of 10,000+ AI tools, in the browser and in native desktop AI apps. | Discovers AI tools in use and dynamically detects emerging AI components across web apps and the browser; claims 15,000+ AI tools. | Day-one inventory of AI tools in use; states coverage of 1,000+ AI surfaces. |
| Data leakage prevention | Prompt inspection at submit, before the prompt leaves the device; block or redact on prompts and file uploads. | Sanitises and redacts sensitive data (PII, PHI, financial, source code) before it reaches an LLM; automatic anonymisation claimed on its employees page. | Model-based detection of sensitive data in context, moving beyond regex pattern matching; real-time prompt redaction claimed. |
| Real-time response | Block, redact or coach at submit; real-time coaching at the moment of a risky prompt, in the browser and in native AI apps. | Blocks prompt injection, jailbreaks, and data exfiltration in real time; alerts on policy triggers; coaching claimed on its employees page. | Per-policy choice to block in real time, warn the employee with context, or log silently. |
| Hard block with no user override | Yes: hard block on prompts and file uploads with no user override. | Block and automatic anonymisation are policy options; an override-free block is not publicly documented. | Block is a per-policy option; business-justification prompts let the user proceed where enabled. |
| Layout-preserving file redaction | Yes: layout-preserving DOCX, XLSX and PDF redaction with length-matched entity replacement. | Sanitises prompt content; layout-preserving DOCX, XLSX and PDF redaction is not publicly documented. | Prompt redaction claimed; file or document redaction not claimed. |
| Native desktop AI apps | Native endpoint app for Windows and macOS intercepts the ChatGPT, Copilot and Claude desktop apps. | Dedicated AI endpoint agent for local LLMs and MCP servers (February 2026); interception of the ChatGPT, Copilot or Claude desktop apps is not publicly documented. | Desktop client names Claude Desktop, ChatGPT Desktop, Cursor, Codex, Claude Code, GitHub Copilot and Ollama. |
| Application & agent security | Not an LLM firewall; AI agent and MCP inspection on the endpoint app ships in limited rollout. | Protects homegrown LLM apps and AI code assistants (e.g. GitHub Copilot); MCP security for agents. | MCP Gateway intercepts agent traffic to discover servers/clients and enforce policy. |
| Deployment model | Browser plugin for Chrome, Edge, Firefox and Safari plus native endpoint app for Windows and macOS, pushed with your existing deployment tooling; first signal within hours. | Delivered as SaaS or self-hosted / on-premises; Chrome browser extension deployed via MDM. | Browser extension, desktop client, and MCP gateway; rollout via Intune, JAMF, Kandji, or GPO. |
| Self-serve trial | 30-day self-serve free trial; deploys with IT's existing tooling and shows a first signal within hours. | Demo only; no self-serve trial (as of September 2026). | Book a demo only; no self-serve trial (as of September 2026). |
| Data residency choice | Seven Aona-managed hosting regions: Australia, France, the UK, Germany, the US, Singapore and Hong Kong. | SaaS or self-hosted; managed hosting regions are not publicly documented. | EU and US hosting options. |
| Ownership & stage | Independent and purpose-built for Workforce AI Security. | Acquired by SentinelOne (acquisition completed September 2025); now sold as Prompt Security from SentinelOne through the Singularity platform. | Independent startup founded in 2023; raised a $17.5M Series A led by Next47 in October 2024. |
Sources: prompt.security and harmonic.security (vendor sites and trust pages) and Harmonic's AWS Marketplace listing; SentinelOne's acquisition of Prompt Security completed September 2025; Harmonic Security's $17.5M Series A led by Next47, October 2024. Competitor facts re-verified 17 September 2026. Verify current details with each vendor.
The verdict for employee AI use
Aona wins the employee AI use criteria on this page: a hard block on prompts and file uploads with no user override, layout-preserving DOCX, XLSX and PDF redaction, real-time coaching at the prompt, coverage of the ChatGPT, Copilot and Claude desktop apps, seven Aona-managed hosting regions and a 30-day self-serve trial. Prompt Security is for application-side AI security across homegrown LLM apps, code assistants and agents, sold through SentinelOne's Singularity platform since September 2025, and its employee controls are demo-led with no self-serve trial (as of September 2026). Harmonic Security is for point-of-use governance with block, warn or log per policy and business-justification prompts, and its published materials stop at prompt redaction, with evaluation that starts at a demo request.
Where Aona wins: employee AI use
Hard block on prompts and file uploads with no user override, layout-preserving DOCX, XLSX and PDF redaction, real-time coaching at the prompt, coverage of the ChatGPT, Copilot and Claude desktop apps, seven Aona-managed hosting regions and a 30-day self-serve trial.
What Prompt Security is for
Application-side AI security across homegrown LLM apps, AI code assistants and agentic AI, alongside employee controls, sold through SentinelOne's Singularity platform since September 2025. Its employee controls are demo-led, with no self-serve trial (as of September 2026), and an override-free block is not publicly documented.
What Harmonic Security is for
Point-of-use governance on the endpoint with model-based detection and block, warn or log per policy, including business-justification prompts that let a user proceed. Its published materials stop at prompt redaction, and evaluation starts at a demo request (as of September 2026).
Why buyers pick Aona for employee AI use
Four differentiators the other two do not document, each stated against the mechanism Prompt Security and Harmonic publish.
Hard block with no user override
Prompt Security documents block and automatic anonymisation as policy options and does not document an override-free block. Harmonic documents block, warn or log plus business-justification prompts that let a user proceed. Aona's block on prompts and file uploads cannot be dismissed by the employee.
Files stay usable after redaction
Aona redacts DOCX, XLSX and PDF uploads with the layout intact and length-matched entity replacement. Prompt Security sanitises prompt content; Harmonic claims real-time prompt redaction. Neither documents layout-preserving file redaction.
Trial before procurement
30-day self-serve trial, deployed with IT's existing tooling and a first signal within hours. Prompt Security is demo-only with no self-serve trial; Harmonic routes evaluation to a demo request (as of September 2026).
One control point, on the device
Aona's browser plugin for Chrome, Edge, Firefox and Safari and native endpoint app for Windows and macOS inspect the prompt at submit, with seven Aona-managed hosting regions to choose from. Prompt Security's employee coverage runs through a Chrome extension plus a February 2026 endpoint agent for local LLMs and MCP servers; Harmonic offers EU and US hosting.
Scope: Aona secures employees' use of AI tools. It is not an LLM firewall, an AI-SPM tool or a red-teaming product for AI you build, which is Prompt Security's application-side ground. Aona needs its plugin or endpoint app on managed devices, so personal and unmanaged devices are out of scope; there is no iOS or Android coverage; and AI agent and MCP inspection ships in limited rollout on the endpoint app, not general availability.
- ✓SOC 2 Type II certified
- ✓30-day self-serve trial
- ✓10,000+ AI tools tracked
- ✓7 Aona-managed hosting regions
FAQ
Prompt Security vs Harmonic Security
What is the main difference between Prompt Security and Harmonic Security?
Is Prompt Security part of SentinelOne now?
Does Harmonic Security cover shadow AI and agents?
Which one should I choose for employee AI use?
Do I need Aona if I already have Prompt Security or Harmonic Security?
How do the three compare on trial, evaluation path and data residency?
Test the block and the redaction
on your own prompts
Start a 30-day self-serve trial and watch Aona inspect a prompt at submit, block it with no override and redact a DOCX with the layout intact. Or book a demo and bring the same test you would put to Prompt Security and Harmonic.