Prompt Security alternative: masking that gives the data back

A finance analyst pastes a supplier dispute into ChatGPT at 4:50 pm on a Friday. It contains a name, an IBAN and the amount, CHF 2,400. A blocking tool stops the paste and she rewrites it by hand, or she opens ChatGPT on her phone instead. A redacting tool sends [NAME] and [IBAN], and the draft she gets back has holes in it. A masking tool sends tokens and puts the real values back in the draft. That difference is most of this comparison.

Maskflare wrote this page. Prompt Security is a capable product with a big parent company, and it's the better fit for some buyers.

What is Prompt Security?

Prompt Security is an AI security company that SentinelOne acquired; SentinelOne's filings show the deal closed on 5 September 2025. Its site now brands it “Prompt Security from SentinelOne”. It covers two main use cases. For employees, a browser extension monitors prompts, file uploads and responses in AI tools, and its own blog describes flagging sensitive data and redacting or warning before submission rather than blocking whole tools. For homegrown apps, an API screens inputs and outputs for prompt injection, data exfiltration and policy violations. Its guardrails include sensitive data, secrets, prompt injection, topic detection and custom rules. It also publishes an open-source prompt fuzzer for testing system prompts.

When is Prompt Security the better choice?

• You're a SentinelOne shop. If your endpoint security already runs on SentinelOne, buying GenAI security from the same vendor means one contract, one console and one support path.
• You want model-based jailbreak and topic detection. Prompt Security screens for injection, jailbreaks and off-topic use with classifiers. Maskflare's injection detection is pattern-based and explainable, and it has no topic filtering.
• You want broad AI usage visibility. Seeing which AI tools employees use, including shadow AI, and governing them by policy is a core use case.
• You want topic and content policies. Blocking conversations about certain topics is outside Maskflare's scope.

When is Maskflare the better choice?

1. You want masking, not just redaction or blocking. Maskflare replaces values with reversible tokens and restores them where the answer repeats them, in the browser and in API responses, including streams. People keep working and the provider never sees the data.
2. You need the app side and the people side under one policy. The gateway, SDKs and LiteLLM guardrail cover your applications. The desktop agent, browser protection and forward proxy cover people. The MCP route and hooks for Claude Code, Cursor and Codex CLI cover agents. One rule set applies to all of them.
3. You want coverage beyond the browser. The desktop agent routes only AI hosts through Maskflare, so apps calling the provider APIs via the system proxy are covered too, not just tabs in Chrome. It's fail-closed by default and needs a console code to uninstall.
4. You're in the EU. Maskflare is EU-hosted by default, with on-premises deployment for enterprise. Prompts and responses are never logged or stored.
5. You need European identifiers. 47 country packs with checksum validation, including all EU-27, and 232 credential formats.
6. You don't want a full security suite. Maskflare is a focused tool you can trial in a day.

Prompt Security vs Maskflare, feature by feature

How do you roll out Maskflare to employees?

1. Create an enrollment token in the console.
2. Deploy the desktop agent with Intune, Jamf or Group Policy. It self-enrolls from managed settings.
3. Pick a compliance profile (GDPR, UK GDPR, PCI DSS v4.0, HIPAA Safe Harbor or US PII), or start in alert mode to see what would be masked.
4. Watch device states (protected, unprotected, stale, revoked) in the console. Users see notifications like “3 items masked in ChatGPT” in the tray app.

The honest objections

“Prompt Security also redacts, so what's the difference?” Redaction removes the value. Masking swaps it for a token that comes back in the answer. For an analyst asking for a draft letter, that's the difference between a usable draft and one full of [REDACTED].

“Browser extensions are easier to deploy than a desktop agent.” Often, yes. Maskflare offers both: browser protection for the web apps, and the desktop agent for broader coverage. The agent installs as an MSI on Windows, a signed and notarized PKG on macOS, or a package on Ubuntu, Fedora and RHEL desktops, and it re-applies its proxy setting within 10 seconds if someone changes it. Its heartbeat reports state and version every five minutes, never URLs or traffic.

“SentinelOne is a much bigger company.” It is, and for some procurement teams that settles it. Maskflare's SOC 2 Type II and ISO 27001 audits are in progress; if a completed report is a hard requirement today, factor it in.

“We need injection protection too.” Then you need a guardrail as well. Maskflare covers the data side; pair it with a guardrail for attacks, or keep Prompt Security for that and use Maskflare for masking.

“What about Microsoft Copilot?” Covered. Maskflare's web coverage is ChatGPT, Claude, Gemini, DeepSeek, Perplexity, Mistral Le Chat and Microsoft 365 Copilot, including Copilot chat and its attachments.

Mask, redact or block: what does the user actually get?

The analyst from the opening asks for a short letter to the supplier. Here's what comes back under each approach:

Every approach has a place. Block is right for API keys and passwords, and Maskflare blocks credential-shaped values in the browser for that reason. Warn works for low-risk data where you want awareness. Redact suits analytics prompts. Mask is for the large middle: everyday work that genuinely needs the data in the output, just not at the provider. In Maskflare you set the action per rule, so one policy can block API keys, mask names and IBANs, and keep only the last four digits of card numbers.

What Maskflare doesn't do

• No topic or off-brand content filtering.
• AI app discovery covers managed devices; unmanaged personal devices are out of reach.
• SOC 2 Type II and ISO 27001 audits are in progress.