Prompt Security built its public identity around enterprise GenAI security in the broad sense: protecting how employees use AI tools (including browser-level controls), protecting the GenAI features companies build into applications, and — per its public materials — governing agent and MCP traffic. In 2025, SentinelOne publicly announced its acquisition of Prompt Security, folding the technology into a larger endpoint-and-enterprise-security platform.

That acquisition is why many teams are re-shopping the category now: some want the SentinelOne integration, others prefer an independent vendor, and others are simply re-running diligence that a change of ownership makes prudent — roadmap fit, platform coupling, pricing model. This post maps the decision. Disclosure first: Praesidia is our product and appears below, held to the same public-claims-only standard as every other entry. As of July 2026, verify everything against vendors' current documentation.

Decide the surface first

"GenAI security" bundles at least three distinct surfaces, and vendors weight them very differently:

  1. Employee usage. Controlling what staff paste into and receive from AI tools — the shadow AI problem — typically enforced at the browser or network layer.
  2. Application content defense. Guardrails on the GenAI features you build: injection detection, data-leak filtering on model inputs and outputs.
  3. Agent-estate governance. Identity, authorization, budgets, audit, and guardrails for autonomous agents and the MCP servers and tools they call — the surface where the OWASP Agentic Top 10 lives.

Prompt Security's public positioning touches all three from an enterprise-security angle. Alternatives make sense when one surface dominates your risk and you want the tool built around that.

The alternatives

Praesidia (disclosed: our product)

Praesidia is built around the third surface: an agent governance control plane where every agent, application, and MCP server holds its own identity, and where policy, bidirectional guardrails, budgets, and rate limits are enforced in-band at runtime with an append-only, hash-chained audit trail. Employee/browser usage control is not its surface — that is an honest non-overlap with Prompt Security's stated scope. Operating-model distinctions, per our public documentation: open-source Apache-licensed core, EU data residency, $0 free tier. The deeper comparison of what a control plane covers is in what is an AI control plane.

Lakera

Lakera's public positioning is focused content defense — prompt-injection detection and moderation via API, with research assets like Gandalf — and public reporting in 2025 announced its acquisition by Check Point. The natural comparison when application content defense is the dominant surface. We survey that category in Lakera alternatives for LLM guardrails.

Zenity

Zenity publicly positions around agentic AI security posture and detection/response for agents built across enterprise platforms (Copilot Studio, Agentforce, low-code environments). It approaches the agent surface from the visibility-and-posture side rather than the runtime-enforcement side — the distinction unpacked in runtime security vs posture management. Fuller survey in Zenity alternatives.

Platform-native security stacks

For organizations standardizing on one ecosystem, the platform vendors' own controls — Microsoft's Entra Agent ID, Purview, and Copilot/Foundry controls being the publicly documented flagship example — cover meaningful ground for AI usage within that estate. The boundary is cross-vendor reach, examined in Microsoft agent governance and independent control planes.

Open-source components

Self-hostable pieces — NeMo Guardrails, Llama Guard classifiers, open MCP gateways — let platform teams assemble a bespoke stack with full inspectability and no vendor coupling. The cost is the assembly and its maintenance: detection tuning, policy plumbing, audit integrity, and operations, per the sober accounting in build vs buy.

How the acquisition changes the calculus

Three practical diligence points when a category vendor is acquired — applicable to any of them, not just this case. Platform coupling: does full value now assume adopting the acquirer's wider platform, and is that platform one you run? Roadmap weighting: public statements after acquisitions signal which surfaces get investment; match them against your dominant surface. Procurement shape: pricing, packaging, and contract vehicles often migrate to the acquirer's model — a gain for existing customers of the acquirer, friction for others. None of these is inherently negative; all are worth asking explicitly rather than discovering at renewal.

Choosing

If employee AI usage is the dominant risk, shortlist enterprise-security-anchored options (Prompt Security within SentinelOne among them) and weigh endpoint integration. If application content defense dominates, shortlist detection specialists and open classifiers, and test on your traffic. If the agent estate dominates — engineer-built agents, tools, MCP servers — shortlist governance control planes (Praesidia's category) and posture platforms, and decide the visibility-vs-enforcement mix. In all three cases, the discriminating test is enforcement depth on agentic flows: whether a policy violation inside a tool call is stopped in-band, not just observed. The RFP checklist provides the full question set.

Common questions

What is Prompt Security known for? Per its public positioning: enterprise GenAI security spanning employee AI usage protection (including browser-level controls), application-level GenAI protection, and agent/MCP traffic governance. SentinelOne publicly announced its acquisition of the company in 2025.

Why do buyers evaluate alternatives after an acquisition? Standard diligence: platform coupling (does value now assume the acquirer's stack?), roadmap weighting across the product's surfaces, and changes to pricing and procurement. Re-shopping after ownership change is prudence, not criticism.

Is Praesidia a like-for-like replacement for Prompt Security? No — the overlap is the agent/application governance surface, where Praesidia enforces identity, guardrails, budgets, and audit in-band. Employee browser-usage control is in Prompt Security's stated scope and not in ours. If both surfaces matter to you, you are comparing portfolios, not products — evaluate accordingly.

What should a proof of concept test in this category? Your dominant surface, adversarially: for agent estates — an unapproved tool call blocked, seeded sensitive data caught inside a tool parameter, a budget hard-stopping a loop, a credential revoked and dead in seconds; for employee usage — policy triggering on real workflows in the browsers your staff actually use.