Pseudonymization vs. anonymization
The two words are often used as if they meant the same thing. In data protection law they don't, and the difference decides whether the rules still apply to your text.
Pseudonymization: reversible with extra information
Pseudonymized data no longer names the person directly, but it can be linked back to them with additional information that is kept separately. The GDPR defines it in Article 4(5). Replacing "Sarah Whitfield" with [PERSON_1] while keeping a list that says which placeholder stands for which name is a textbook example.
Pseudonymized data is still personal data. The GDPR treats pseudonymization as a safeguard that lowers risk, for example when data is shared or processed for research, not as a way out of the rules.
Anonymization: no way back
Anonymized data can no longer be linked to a person by anyone, with any means that are reasonably likely to be used. Recital 26 of the GDPR says the regulation does not apply to such data. The bar is high: removing names is often not enough, since combinations of other details (age, town, job, dates) can still single someone out.
What a text anonymizer gives you
- Placeholders and hashes are pseudonymization. Placeholders keep a mapping in your browser so you can restore the original values in an AI's answer; hashes give the same value the same code every time.
- Masks and fake data throw the replaced values away. Whether the result is anonymous depends on what is left in the text. Automatic detection can miss values, and indirect details may still identify someone.
So no tool can promise anonymization of free text by itself. What it can do is find the direct identifiers reliably, let you review and add what it missed, and keep everything on your device while doing so.
In practice
- For an AI prompt whose answer you want back, use placeholders and treat the result as personal data that has been made much less revealing.
- To share text for good, use masks or fake data, then read the result and generalize indirect details by hand.
- Keep exported mapping files as carefully as the original data: they are the key that reverses the pseudonymization.
This page explains terms; it is not legal advice. For decisions about your obligations, ask your data protection officer or a lawyer.