Prompt Security Alternative - One Plane for Agent Controls
Prompt Security covers a broad slice of LLM protection. Agentshield is the agent-first alternative that unifies firewall, permissions, monitoring, and audit for agents that take actions.
Direct answer
A Prompt Security alternative is a tool that protects LLM and agent usage with an agent-action focus. Agentshield is a runtime control plane for agents that take actions: it blocks prompt injection, enforces tool and data permissions, gates high-risk actions for a human, monitors in real time, and writes an immutable audit trail. It is stack-neutral, self-serve, and priced on the page.
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Where Prompt Security is strong
Prompt Security offers a broad LLM security platform covering prompt-injection and data protection across enterprise GenAI usage.
Where Agentshield is the alternative
Agentshield is built specifically for autonomous agents that call tools and take actions, not just chat. It unifies a prompt-injection firewall, least-privilege tool and data permissions, human-approval gates, monitoring, and an immutable audit trail, and it is self-serve with transparent pricing rather than sales-gated.
Side by side
Agentshield vs Prompt Security, honestly.
| Dimension | Agentshield | Prompt Security |
|---|---|---|
| Agent action focus | Built for agents that call tools and take actions. | Broad LLM and GenAI usage protection. |
| Tool and data permissions | Least-privilege permissions at the action boundary. | Centered on prompt and data protection. |
| Human approval gates | Built-in gates for refunds, deletes, and sends. | Not the core focus. |
| Audit trail | Immutable, exportable record of every action. | Logging across its platform. |
| Pricing | Transparent, self-serve. | Sales-led enterprise. |
Comparison reflects our understanding of publicly available information and is meant to be fair. Vendors evolve; verify the latest before deciding.
How Agentshield and Prompt Security differ in practice
Prompt Security built a broad enterprise platform for generative AI security, covering prompt-injection and data protection across how a whole organization uses AI tools. SentinelOne completed its acquisition of Prompt Security on September 5, 2025, and is folding that capability into its Singularity platform, positioning it as part of a larger endpoint and enterprise security suite. For a company standardizing on SentinelOne, that consolidation is a real advantage.
Agentshield is deliberately narrower and closer to the agent. It is the runtime control plane a developer drops directly in front of an agent that calls tools and takes actions, to block prompt injection, enforce least-privilege tool and data permissions, gate high-risk actions for a human, and write an immutable audit trail. It is stack-neutral and self-serve, with prices on the page, and it does not assume you are buying a platform.
The honest split: a Prompt Security deployment now lands as part of a SentinelOne enterprise motion aimed at securing AI usage across a company. Agentshield is bought by the team shipping a specific agent and wanting a tight action boundary around it this quarter.
When the SentinelOne platform is the better fit
Pick the SentinelOne and Prompt Security route when you are already a SentinelOne customer and want AI security under the same console, contract, and agent you already run, when your priority is org-wide visibility into how employees use generative AI tools, or when a security organization wants GenAI protection consolidated into a broad endpoint and enterprise platform.
Pick Agentshield when the job is to govern a specific agent that takes actions, when you want to be enforcing without a platform commitment or a procurement cycle, and when transparent, self-serve pricing matters. Some teams run both: the SentinelOne platform for enterprise-wide AI usage, Agentshield as the runtime guardrail around the production agents that call tools and move data.
What changes for a buyer after an acquisition
Prompt Security is one of six independent companies in this category to be acquired since 2024, so this is worth understanding as a pattern rather than a one-off. If you shortlisted a startup and it was bought, three things change and none of them are announced in a press release.
| What changes | What it means in practice | What to ask |
|---|---|---|
| Buying motion | A standalone contract becomes a line in a platform agreement, usually with a longer cycle and a larger minimum | Can I still buy this capability on its own, and at what floor? |
| Roadmap priority | Features now compete for engineering time against the acquirer's platform priorities, which are rarely your priorities | Which of the features I am buying for are on the committed roadmap in writing? |
| Integration timeline | Deep integration takes time. In the interim you may run a product that is neither fully standalone nor fully native | Is this shipping inside the platform console today, or is it still a separate deployment? |
| Support and account team | Founding engineers who answered questions directly are absorbed into a larger organization | Who owns my technical escalation path now, and what is the response commitment? |
| Pricing over time | Bundled pricing can be better value or can force you into tiers you do not need | What does renewal look like if I only want this one component? |
To be fair to SentinelOne, consolidation here has genuine upside: one console, one agent on the endpoint, and a vendor with the balance sheet to still be shipping in five years. That is a real argument and for many security organizations it is the deciding one. The counter-argument is only that a team shipping one production agent this quarter is buying a platform to solve a component problem. We keep an updated map of who owns what across this market in our writeup of AI agent security companies, and the same acquisition pattern is covered on Lakera alternatives and Robust Intelligence alternatives.
FAQ
Common questions.
Did SentinelOne acquire Prompt Security?
Yes. SentinelOne announced a definitive agreement on August 5, 2025 and completed the acquisition on September 5, 2025. Reported deal values vary between roughly 180 and 250 million dollars depending on whether the figure comes from the announcement or the filed consideration, so treat any single number with caution. Prompt Security is now part of the Singularity platform.
What are the best Prompt Security alternatives in 2026?
It depends which half of the problem you have. For governing employee use of AI tools across a company, the closest comparables are broad enterprise platforms: SentinelOne itself, Cisco AI Defense, Palo Alto Prisma AIRS and Zscaler. For controlling agents your own team builds and runs, the field is narrower and includes Agentshield, Lasso Security, Zenity and open-source guardrail libraries you assemble yourself.
Is Prompt Security still available after the acquisition?
The capability continues inside SentinelOne rather than as an independent purchase. Practically, that changes three things worth planning for: procurement runs through SentinelOne, the roadmap now serves Singularity platform priorities, and pricing is bundled rather than standalone. None of that is a criticism, but it is a different buying motion than a startup contract.
What is an alternative to Prompt Security for AI agents?
Agentshield is an agent-first alternative to Prompt Security. Rather than a broad enterprise GenAI platform, it is a runtime control plane you put directly in front of an agent that takes actions: it blocks prompt injection, enforces tool and data permissions, gates high-risk actions for human approval, monitors in real time, and keeps an immutable audit trail. It is stack-neutral, self-serve, and priced on the page.
Is Agentshield self-serve, unlike an enterprise platform?
Yes. Agentshield is self-serve with transparent pricing, so you can deploy it in front of an agent in an afternoon without a sales call or a platform commitment. Enterprise options like SSO and on-prem are available, but they are not a prerequisite for getting started. That is the main practical contrast with a sales-led enterprise suite.
Does Agentshield cover employee use of AI tools like Prompt Security?
No, and we are honest about that boundary. Governing how employees paste data into ChatGPT or Copilot is a shadow-AI and enterprise-usage problem that a platform like SentinelOne with Prompt Security addresses well. Agentshield secures the agents you build and run, the ones that call tools and take actions. If that is your problem, Agentshield is the tighter fit; if it is employee AI usage, it is not.