Practical guide · By Aurelio Avila · October 15, 2026
A PII redaction extension for AI chats: what runs on your device
A browser extension that redacts personal data before it reaches ChatGPT has to read what you type. That makes it worth asking hard questions before you install one, including ours. Here are the questions, and Redaxa's answers, each one checkable.
Four questions for any PII redaction extension
- Which sites can it read? Chrome lists an extension's site access on its details page. A redaction tool for AI chats needs the AI sites, not every page you open.
- Where does detection run? In your browser, or on the developer's server? If on a server, is the text stored or passed to another AI?
- Does it change your text silently? Automatic rewriting can break a prompt without you noticing. You should see what was found and decide.
- What does it actually detect, and what does it miss? A list of supported data types is a start; a list of known misses is better.
Redaxa's extension, question by question
| Sites it can read | Its content script is declared for four sites only: chatgpt.com, claude.ai, gemini.google.com and www.perplexity.ai. Its permissions are storage and clipboardWrite; it requests no other host access. |
|---|---|
| Where detection runs | Free checks run Redaxa's engine inside your browser: the text you check is not sent anywhere. With a Pro or Business plan, checks run on Redaxa's server so your protected terms and team policies apply; the text is not stored and not forwarded to an AI provider. |
| When it checks | When you press Enter or Send on a supported site, before anything leaves the browser. You can switch this off in the extension's popup ("Check automatically before sending") and check text by hand instead. |
| What happens on a finding | A notice lists what was found. You choose Replace with redacted version, Send anyway, or close the notice and edit; the message stays unsent until you decide. Business admins can set a category to block sending. |
| Account | None needed for free checks, and no daily limit. |
| Interface languages | English, Italian, Spanish, French and German. |
What it detects, and what it misses
The extension uses the same engine as the web check, the Windows app and the repository check. In one pass it looks for:
- Personal data: email addresses, phone numbers, names after a greeting, English-format street addresses, IPv4 addresses, US Social Security numbers, UK National Insurance numbers and Italian fiscal codes.
- Financial data: card numbers (Luhn-checked), IBANs (mod-97-checked) and crypto wallet addresses.
- Credentials: API keys and tokens from more than a dozen providers, passwords, private keys and secrets in configuration. See how to stop API keys leaking into AI prompts.
Known limits, stated on the detector pages with real examples: a name is detected only right after a greeting such as "Hi" or "Dear"; addresses are recognised only in the English house-number-first format; the phone rule also matches some order and invoice numbers. For client and project names, use protected terms. The full list is in the detection reference.
Try it in two minutes
- Add Redaxa from the Chrome Web Store and pin it from the puzzle icon.
- Open ChatGPT, Claude, Gemini or Perplexity and type a fictional test, for example
Email the contract to maria.rossi@example.com. - Press Enter. The notice shows the email and offers
Email the contract to [EMAIL].
Pro and Business start with a 3-day free trial: a card or another payment method is needed, nothing is charged for 3 days, and you can cancel before it ends from Manage subscription. See plans.
FAQ
Can the extension read every website I visit?
No. Its content script is declared only for chatgpt.com, claude.ai, gemini.google.com and www.perplexity.ai, and its only permissions are storage and clipboardWrite. You can confirm this in the extension's details page in Chrome.
Does it change my message without asking?
No. When it finds something, it shows a notice before the message is sent and you choose: replace the text with the redacted version, send anyway, or close the notice and edit. Business admins can set a policy that blocks sending for a category.
Which languages does it support?
The extension's interface is available in English, Italian, Spanish, French and German. Detection patterns are the same for every language; the national identifiers it knows are US Social Security numbers, UK National Insurance numbers and Italian fiscal codes.
What does it cost?
Free checks in the extension are unlimited and need no account. Protected terms and team policies come with Pro or Business.