Best Chrome Extensions for Masking Personal Data in AI Chatbots (2026 Comparison)
If you've searched for a way to mask personal data before it reaches ChatGPT, Claude, or Gemini, you've probably found a handful of Chrome extensions that claim to do the job. They all sound similar on the surface. The differences are in what they detect, how they process your data, and what they cost.
We built PiiBlocker, so we're biased. But we also think the best way to earn trust is to be honest about how every option works, including where others do things differently. Here's what we found when we tested the main tools in this space.
What to look for in a PII masking extension
Before comparing specific tools, these are the questions that actually matter:
Where does detection happen? If the extension sends your text to an external server for analysis, your data has already left your device before masking occurs. Local processing means detection and masking happen entirely in your browser.
How many PII types are detected? Regex-only tools catch structured data like credit cards and SSNs well, but often miss names, medical conditions, and contextual PII. NER-based detection understands context and catches more.
What platforms are supported? Some tools only work on ChatGPT. If you also use Claude or Gemini, you need multi-platform support.
Is there a free tier with real functionality? Some tools offer free trials or token-limited free tiers. Others are genuinely free for core features.
The tools compared
PiiBlocker (by PiiBlock)
Platforms: ChatGPT, Claude, Gemini (all in free tier)
Detection method: Hybrid NER-based detection plus regex pattern matching. The NER model provides contextual understanding so it can distinguish between a credit card number being submitted as real data versus a number referenced in an instruction.
PII types: 15+ including credit cards (Luhn validation), SSNs, API keys (OpenAI, AWS, GitHub, Stripe), passwords, names, addresses, phone numbers (US and UK), emails, dates of birth, ages, salaries, medical conditions, bank accounts, and UK National Insurance numbers.
Processing: 100% local. PiiBlock does not operate any servers. There is no API, no database, no cloud infrastructure. Detection, masking, and unmasking all run in the browser.
How masking works: Before your message is sent, a dialog separates detections into auto-protected (critical PII) and user-choice (soft PII). You decide what to mask. The AI receives placeholder tokens like [PERSON_A] and [CREDIT_CARD_1]. When the AI responds, PiiBlocker swaps placeholders back to real values automatically.
Unique features: Right-click manual masking for anything automation misses. Personal dictionary to teach it custom terms. AES-256-GCM encryption for mapping data with auto-expiry after 4 hours.
Pricing: Free forever for all core features. No usage limits, no account required. Pro tier coming at $4.99/month with automatic soft-PII masking, privacy dashboard, and additional platform support.
Limitations: No support yet for DeepSeek or Perplexity (planned for Pro). The extension is Chrome-only.
Caviard
Platforms: ChatGPT and DeepSeek
Detection method: Regex pattern matching with multi-language support.
PII types: Names, emails, payment data, and other common identifiers. Supports different languages and layouts.
Processing: 100% local. Masking runs in the browser.
How masking works: Caviard scans text in real-time and flags sensitive data before sending. Masked prompts use placeholders that preserve context. Press Alt+R (Option+R on Mac) to reveal original text.
Pricing: Free tier available. Enterprise pricing for team features.
Limitations: Does not support Claude or Gemini in the free tier. Detection is regex-based without NER, which may miss contextual PII like names in unstructured text.
ChatWall
Platforms: ChatGPT, Claude, Gemini, Grok, Copilot, DeepSeek
Detection method: Regex and NLP-based detection. Claims 25+ entity types.
PII types: IBAN, SSN, API keys, names, emails, phone numbers, and more. Manual masking available for missed items with a favorites feature for automatic future detection.
Processing: 100% local for the browser extension. Also offers an on-premise "Box" server for enterprise deployments.
How masking works: Users type inside a secure overlay window that the host website cannot access. The original text is never exposed to the chat site's scripts. The AI responds with tokens and ChatWall restores original values in a secure overlay.
Unique features: The overlay approach means the chat website's own scripts never see your unmasked text. This is architecturally different from extensions that mask within the chat input field itself.
Pricing: Free tier for personal use. Premium tier with license key. Enterprise "Box" deployment available.
Limitations: The overlay approach changes the typing experience. Users type in a separate window rather than the native chat input.
Cloak.business
Platforms: ChatGPT, Claude, Gemini, DeepSeek, Perplexity, Abacus.ai
Detection method: API-based processing through the Cloak.business service.
PII types: Names, emails, phone numbers, addresses, and other identifiers.
Processing: Uses the Cloak.business API. Data is sent to their servers for anonymization, then the anonymized version is sent to the AI.
How masking works: The extension intercepts messages in real-time on supported platforms. Custom connectors can be developed for any website.
Pricing: Free plan with 200 tokens per month. Paid plans for higher usage.
Limitations: Data is processed through external servers, not locally. The 200 token/month free limit is restrictive for regular use. Chrome extension is currently in preview.
Privacy Protector for ChatGPT
Platforms: ChatGPT only
Detection method: Manual dictionary-based replacement.
PII types: Whatever the user defines in their personal dictionary.
Processing: 100% local. All data stored in the browser.
How masking works: Users create a dictionary of sensitive words and their replacements. The extension swaps them before sending. Supports automatic and manual modes.
Pricing: Free.
Limitations: No automatic PII detection. Users must manually define every term they want masked. Only works on ChatGPT. No support for Claude, Gemini, or other platforms.
Side-by-side comparison
| Feature | PiiBlocker | Caviard | ChatWall | Cloak | Privacy Protector |
|---|---|---|---|---|---|
| ChatGPT | ✅ | ✅ | ✅ | ✅ | ✅ |
| Claude | ✅ | ❌ | ✅ | ✅ | ❌ |
| Gemini | ✅ | ❌ | ✅ | ✅ | ❌ |
| DeepSeek | ❌ | ✅ | ✅ | ✅ | ❌ |
| Local processing | ✅ | ✅ | ✅ | ❌ | ✅ |
| Auto PII detection | ✅ | ✅ | ✅ | ✅ | ❌ |
| NER-based detection | ✅ | ❌ | ✅ | — | ❌ |
| 15+ PII types | ✅ | ✅ | ✅ | — | Manual only |
| Native chat typing | ✅ | ✅ | ❌ (overlay) | ✅ | ✅ |
| Auto response unmasking | ✅ | Alt+R toggle | Overlay reveal | ✅ | Manual reverse |
| Right-click manual mask | ✅ | ❌ | ❌ | ❌ | ❌ |
| Personal PII dictionary | ✅ | ❌ | Favorites | ❌ | ✅ |
| AES-256 encrypted storage | ✅ | ❌ | — | — | ❌ |
| Auto-expiring mappings | ✅ (4 hrs) | Periodic | — | — | ❌ |
| Zero server architecture | ✅ | ✅ | Extension yes, Box no | ❌ | ✅ |
| Free unlimited | ✅ | Limited | Limited | 200 tokens/mo | ✅ |
| No account required | ✅ | ✅ | ✅ | ❌ | ✅ |
Which one should you use?
If you use ChatGPT, Claude, and Gemini and want free, unlimited, local PII masking with automatic detection: PiiBlocker covers all three platforms in the free tier with no usage limits.
If you primarily use ChatGPT and DeepSeek: Caviard supports both and has solid regex-based detection.
If you need the widest platform support: ChatWall supports six platforms including Grok and Copilot. The overlay approach also provides an extra layer of isolation from the chat website's scripts.
If you need enterprise deployment with a managed server: ChatWall's "Box" product or Cloak.business's API approach may fit better than a browser extension.
If you only use ChatGPT and prefer full manual control: Privacy Protector lets you define exactly what gets masked using a personal dictionary.
There is no single best tool for everyone. The right choice depends on which AI platforms you use, whether local processing matters to you, and how much automation you want.
PiiBlocker is a free Chrome extension that masks personal data before it reaches AI chatbots. 100% local processing, no servers, no data collection. Install from Chrome Web Store →