Ukrainian developer Andrii Kozak has created the ChatDataMask browser extension, which allows safe use of artificial intelligence in recruiting, legal cases, and analytics. The tool automatically masks private information before the text reaches the servers of AI platforms.
From routine recruiting to the issue of confidentiality
The idea of creating ChatDataMask came to Andrii during his own practice of hiring teams, when he encountered a large volume of routine work and the risks of leaking candidates' data.
"When I was selecting candidates for the team, resumes, interviews, and feedback took a lot of time. Today, a significant part of this work is done by ChatGPT. But every time a resume flies into the chat, it also sends the name, phone number, email, and salary of a person who doesn't even know about it," noted Andrii Kozak.
To solve this problem, the developer created an extension for Chrome that works on a local-first principle. Anonymization, replacement of data with tokens, and their subsequent restoration occur exclusively locally in the user's browser — the information does not reach AI models for training or any third-party servers.
How ChatDataMask works: 40 seconds to mask
As an example, the developer showed a real scenario of using the tool in a recruiter's work.
Text analysis: the user pastes a resume or screening notes into the chat — the extension automatically highlights personal data (names, contacts, salary, etc.).
One-click masking: after pressing the Mask 5 values button, the tool replaces real data with tokens (for example, instead of "Jane Smith" ChatGPT sees [NAME_1]).
Response generation: artificial intelligence processes the anonymous text and creates a conclusion for the hiring manager without losing context.
Data restoration: with one click, the user copies the AI's response, where the tokens are automatically replaced back with the real data for insertion into a work document.
If the user accidentally presses the send message button with unmasked data, ChatDataMask will stop the process and suggest first hiding the sensitive information.
What exactly the tool recognizes and hides
The extension is designed to protect against data leaks and supports the requirements of European GDPR and EU AI Act standards.
personal and contact data: full names, phone numbers in international format (based on libphonenumber-js), e-mail, home addresses, passport numbers, IDs and tax numbers (TIN/VAT);
financial details: bank card numbers, IBAN accounts, SWIFT codes and cryptocurrency wallet addresses (Bitcoin, Ethereum and other EVM networks);
technical information: IP and MAC addresses, API keys, access tokens.
Platform support and availability
The extension is completely free. The interface and data recognition module support five languages: Ukrainian, English, Polish, German, and Spanish.
ChatDataMask has direct integration with the interfaces of ChatGPT, Claude, and Google Gemini (a special protective shield is displayed in the input field). For other services, such as Microsoft Copilot, masking and reverse deanonymization are performed through a convenient browser side panel.
ChatDataMask can be installed from the Chrome Web Store at the link.