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GDPR · Article 4(5)

Pseudonym­isation under the GDPR.

Replace names and other personal data with fixed labels such as ⟦Person 1⟧. You keep the reversal key separate. That way you share or edit a document without showing the people, and restore the real data later.

Try for free How it works

1,000 free credits after confirming your email address. Detection without AI, processed in Europe.

An example

Same person, same label everywhere.

After pseudonymisation

⟦Person 1⟧ calls ⟦Person 2⟧ tomorrow. You can reach ⟦Person 1⟧ at ⟦Email 1⟧.

Original

Sofie Peeters calls Jan Claes tomorrow. You can reach Sofie Peeters at sofie.peeters@example.com.

What the GDPR says

Pseudonymising is not anonymising.

Article 4(5) GDPR defines pseudonymisation as processing personal data so that it can no longer be attributed to a person without additional information. That information is kept separately and protected.

The key is kept apart

In anonimize this is the reversal key. You keep it away from the document, as a file or in a project.

It is still personal data

For anyone who can re-identify it, the GDPR still applies. Only anonymous data falls outside it (Recital 26).

A recognised measure

The GDPR names pseudonymisation for data protection by design (Article 25) and for security (Article 32).

How it works

Pseudonymise in four steps.

  1. Choose

    Pseudonymise

    For text or files, in the document language.

  2. Replace

    Fixed labels

    Within a project the same person gets the same label everywhere.

  3. Keep

    The key apart

    Per document or per project. Without the key the labels point to no one.

  4. Restore

    Real data back

    Paste the edited text into Restore text. Restoring is free.

When to pseudonymise

Useful when you need the data back.

AI tools

Let ChatGPT, Claude or Copilot summarise a text, then put the names back.

Sharing files

An outside party only gets what it needs.

Analysis

Work with real documents without real names.

Linking back

Link a conclusion to the right person.

Price

You only pay for replacements.

1 credit per changed word

A label replacing a two-word name costs 2 credits.

Restoring is free

Checking, downloading and restoring cost nothing.

1,000 free credits

Once per organisation. Then from € 5 a month.

Questions

Common questions

Is pseudonymised data still personal data?

Yes, for anyone who can re-identify it with the key. In 2025 the Court of Justice held that it need not be personal data for a recipient who cannot reasonably identify the people. For you as the key holder, the GDPR applies.

Pseudonymise or anonymise?

Pseudonymise when you want the real data back later. Anonymise when you publish or hand the data over for good. Anonymisation cannot be undone.

Where do I keep the reversal key?

You choose per processing run: a key per document that you download, or a project key. Never store it with the document you share.

Can I restore an AI answer?

Yes. Paste the answer with the labels into Restore text and choose the right processing run or key. Ask the AI tool to keep the labels unchanged.

Does anonimize make my processing GDPR compliant?

Not on its own. Pseudonymisation is one measure among several. You remain responsible for the legal basis, informing people and checking the result.

Sources

This page is general information, not legal advice.

Get started

Pseudonymise your first document.

Create an account. After confirming your email address you get 1,000 free credits, once per organisation.

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