For small companies that use ChatGPT, Copilot and other AI chats

Use AI at work without leaking customer data

LLM Mask checks what your team pastes or types into AI chats, on their own computer, and swaps names, IBANs, citizen numbers and passwords for placeholders. When they copy the answer, the real details come back.

Add to Chrome – free

No account. No server. Nothing is sent to us.

On your computer

What you paste

Mail Pieter Hendriks, IBAN NL91 ABNA 0417 1643 00

What the AI receives

Mail [NAME_1], IBAN [IBAN_1]

Works on

ChatGPT
Claude
Gemini
Copilot
Perplexity
Mistral
Grok
DeepSeek
Meta AI

In Chrome and Edge. On phones: a free web page that does the same check.

The risk

Your team already uses AI. The risk is one paste away.

A customer email, a spreadsheet row, a patient note: pasted into a chat to save time. Once it is sent, it sits on someone else's servers. Most companies have no rule for this, and the ones that do can't check it.

Customer names, email addresses and phone numbers
Citizen numbers (BSN), IBANs and card numbers
Health information and medical codes
Passwords, API keys and access tokens
Your own client names, project names and internal terms

How it works

One message, from start to finish

Everything happens in the browser on the employee's computer.

AI chat, on your computerNothing is sent to us

You paste

Mail Pieter Hendriks, IBAN NL91 ABNA 0417 1643 00

Plays by itself. Click a step to take over.

Diagram: text is checked on the employee's computer, only placeholders go to the AI chat site, and the real details are filled back in when the answer is copied. LLM Mask's makers receive nothing. — The full picture
Where each detail goes, and where it never goes. Click to enlarge.

Features

Built for the way people actually work

Ask first, or replace automatically

Show what was found and let the person choose, or swap details straight away. The dialog coaches people at the moment it matters. Passwords and keys can never be sent as they are.

Checks typed messages too

Not just pastes: a message is checked again when someone presses Enter or the send button.

Real details back on copy

Copy an answer and the placeholders become the real names and numbers again, only on your computer.

Spreadsheets: column names only

Paste a table and LLM Mask offers to send just the headings, or the table without its personal columns. Enough for a formula or an analysis plan; the personal data stays with you.

Your own company terms

Add client names, project names or internal domains. They are replaced however someone writes them: in other capitals, with a dash or underscore, run together or without accents.

Files and downloads

Text, Word, Excel and PowerPoint files are checked inside and can go as a cleaned copy; with LLM Mask Plus also PDFs, scans and photos. Other files are allowed, asked about or blocked by your setting. Downloads from AI chats can be recorded or blocked.

Warns about suspicious answers

If a copied answer contains hidden characters or instructions aimed at another program, LLM Mask points it out.

Eleven languages

English, Dutch, German, French, Spanish, Arabic, Italian, Portuguese, Turkish, Hindi and Japanese, following the browser's language.

Photos lose their hidden data

Before a photo goes into an AI chat, LLM Mask removes its GPS location, date, camera model and other hidden data. The picture itself stays as it is.

Your client and staff lists

Import a name export from your customer or payroll system and every name on it is recognised, however unusual. The list stays on that computer.

Source code: your choice

Code can carry hostnames, keys and colleagues' names. A paste that looks like code is let through, asked about first or blocked, as you set it.

See what each placeholder stands for

A small pill on the chat page opens a panel with the real details behind the placeholders on that site, to look up, copy or forget.

Safe dictation

Speak to the AI. Your voice stays on your computer.

The voice mode and the dictation button of an AI chat send your voice to the AI company. LLM Mask can't check sound, so with Pro you dictate in LLM Mask's own window: your speech becomes text on your computer and is checked before it goes into the chat.

Part of LLM Mask Pro, coming soon

1.Press Alt+Shift+D in the chat
A small LLM Mask window opens. Choose the language you speak and start talking.
2.Speech becomes text on your computer
An open speech model runs in the browser. Spoken numbers are written as digits, so a spelled-out IBAN or phone number is recognised.
3.Checked like a paste
Names, ID numbers, IBANs and other details are replaced with placeholders before the text goes into the chat.
4.The audio is never stored or sent
It stays in the window's memory until you record again or close the window. Need a copy? Save it with every detail found silenced.

20 languages: English, Dutch, German, French, Spanish, Italian, Portuguese, Polish, Romanian, Russian, Ukrainian, Turkish, Arabic, Japanese, Chinese, Indonesian, Hindi, Swahili, Amharic and Somali.
Light on your computer: only the speech model for the languages you dictate is downloaded, once (250 to 670 MB), and it runs only while the dictation window is open.
Companies can block the microphone on AI chat sites, so every spoken word goes through safe dictation.

Speech recognition makes mistakes, especially with unusual names. Read the text before you insert it: a misheard name isn't found by the check either.

What it recognises

The details that should never travel with a prompt

Names
Email addresses and phone numbers
Home and business addresses
Citizen and ID numbers: Dutch BSN, Belgian, German, ID numbers from 20+ European countries, all 54 African countries, Turkey, Latin America, the Middle East, India, Pakistan, China and Japan, US Social Security numbers, Canada's SIN, passports
IBANs and card numbers
Dates of birth
Customer and reference numbers
Energy meter and EAN codes
Health data and medical codes
Passwords, keys and tokens
Your own company terms

On our test set of 994 realistic texts, LLM Mask caught 99.9% of the sensitive details, with false alarms on 0.7% of clean texts.

Privacy

Private by design, not by promise

LLM Mask has no server. There is nothing to hack, subpoena or sell.

Checked on the computer itself

The text you paste is checked in your browser and never sent to us.

Placeholder memory stays in the browser

The link between [NAME_1] and the real name is kept in browser memory and is gone when the browser closes.

No account, no tracking

We don't know who uses LLM Mask or what they paste. The extension only runs on the AI chat sites and asks for just two other permissions: storage and downloads.

Optional reports go to you, not us

Companies can send counts, such as "2 names replaced on chatgpt.com", to their own Google Sheet. Never text, names or values.

Don't take our word for it: check it yourself

Switch off your internet and paste a text into the Try it box on LLM Mask's settings page: names and numbers are still found and replaced. The check needs no connection.
Your IT person can open the browser's developer tools (F12, Network) while pasting into an AI chat: no request goes out from LLM Mask. The only exception is a report address your company sets itself, which receives counts, never text. LLM Mask Plus downloads its model once from our own server and sends no text.
The extension's own code isn't minified or hidden: every line can be read in the installed folder before it is rolled out.

What LLM Mask doesn't do

It reads inside text, Word, Excel and PowerPoint files and offers a cleaned copy; PDFs, scans and photos only with LLM Mask Plus. Other files it asks about or blocks, depending on your setting.
It can't check the ChatGPT or Copilot phone apps; no extension can. Use the free web page on phones.
If your company allows it, someone can still choose to paste the original. That choice is counted in the activity log.
LLM Mask Plus reads printed text in scans and photos, not handwriting; a blurred, skewed or sideways scan can be misread.
Names are found through cue words (Mr, Dear, Name:), common first names and the lists you import; LLM Mask Plus's model finds many more. An unusual name with none of these can be missed: import your client list or add it as a company term.
Placeholders last until the browser closes, and each AI site has its own: the same client can be [NAME_1] today and [NAME_4] tomorrow or on another site. That is because the real names are never written to disk.

Compare

Enterprise AI security, or LLM Mask?

Large security platforms now offer AI data protection too. They work differently, and they are built for a different size of company.

	Enterprise AI security platforms	LLM Mask
Where your text is checked	Typically in the vendor's cloud: your internet traffic is routed through it and inspected there	In the employee's own browser. Nothing is routed anywhere
Who can read the prompts	The platform can extract and classify prompts and answers, for the employer to review	Nobody. Counts and categories only, never the text
When sensitive details are found	The prompt is blocked, or the employee gets a warning	Details are replaced with placeholders, the AI still gives a useful answer, and the real details return when it is copied
What is covered	All apps and devices behind the platform, including desktop apps and developer tools	The listed AI chat sites in the browser, plus a web page for phones
Getting started	A network project, through a sales process	Install in minutes; one rollout file for all computers
Built for	Large enterprises with a security team	Small and medium-sized companies