Guide

Can you ask an AI to anonymize a document?

Not without having already handed it over. For ChatGPT, Copilot or Claude to anonymize a text, you have to send it, which is exactly what you wanted to avoid.

Updated 14 October 2026

The short answer.

No, not safely. Asking an online AI to anonymize a document means sending it that document, with all the data it contains. The anonymization happens after the sending, when it was supposed to come before.

What happens to the document you send.

Depending on the plan and the settings, conversations may be kept, or even used to improve the model. The French Bar’s guide recalls this (p. 8): some tools let you refuse that reuse, but without a verifiable guarantee it calls for vigilance, because the risk to professional secrecy or to GDPR compliance is not ruled out.

A model does not guarantee it finds everything.

The notaries’ IEJ guide stresses that the probabilistic nature of AI does not guarantee the accuracy of its answers (p. 16). The same goes for an instruction like “anonymize this text”: nothing guarantees that a name, a number or a detail was not missed or altered. You would have to reread everything, while the “anonymized” version has already been sent.

Who keeps the mapping?

When an AI replaces names, the mapping between the real names and their stand-ins stays in the conversation, at the provider. With Anoni it stays in an encrypted vault on your machine, and only you restore the real values.

When the question changes: a model on your own machine.

If the model runs on your own machine, the document does not leave: the question is no longer the same. The French Bar’s guide lists, among the ways to guarantee confidentiality, prior anonymization or pseudonymization and installing a model on the firm’s own systems (p. 15). What remains is to review the result.

What to do instead.

Prepare the document before it is sent, on your machine:

Open the document in Anoni, which finds sensitive data offline (a French CamemBERT model plus rules).
Review the detections and choose: realistic pseudonyms, tokens such as “[PERSONNE_01]”, or redaction.
Copy the prepared text into the AI of your choice, then paste the reply back into Anoni to restore the real values.

The limits.

Anoni pseudonymizes or redacts: it does not make data anonymous in the CNIL’s sense, and its detection needs review too. It does not decide for you what may be sent to an AI.

Frequently asked questions

Can Copilot anonymize a PDF?

You would have to send it the PDF, with everything it contains: we are back to the same problem. It is better to prepare the file on your machine, then send only the prepared copy.

Is there a prompt to anonymize a text?

There are some, and for a text with nothing at stake they may be enough. For a confidential document, the problem is not the wording of the prompt, it is sending the document.

What about a paid or professional plan?

It may offer contractual guarantees: the IEJ guide distinguishes free solutions, whose model rests on exploiting the data entered, from paid solutions designed for professional use (p. 28). The document is still transmitted, and it is for you to judge whether that suits its sensitivity.

Does Anoni use an AI to detect the data?

It uses a French detection model (CamemBERT) and rules, running on your machine, offline. Nothing is sent to a server to be analyzed.

References: the French Bar (CNB) guide on ethics and AI (March 2026) and the notaries’ IEJ guide (December 2025), both in French, quoted in our translation. These references are neither a certification nor a validation of Anoni. For the full method: anonymize a document before AI.

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