Free text anonymizer · no upload · no account
Anonymize text before it reaches ChatGPT, Claude, Gemini and other AI models
Paste a text – names, email addresses, phone numbers, IBANs, addresses and IDs become consistent placeholders. Copy it into the AI of your choice, paste the answer back, and the original values return. Everything happens in your browser.
Step 1 · Paste your text
0 / 100.000Step 2 · Review the matches
Solid highlights are pattern matches with check digits – reliable. Dashed highlights are heuristic (names, companies, addresses) – please check them. Click any highlight to ignore it or turn it back on.
Placeholders in this text
Anonymized text
Copy this version into ChatGPT, Claude, Gemini or any other AI model.
Step 3 · Restore the AI answer
Paste the answer that still contains the placeholders. The original values are inserted from the mapping table in your browser – the AI provider never sees it.
Mapping table entries: 0 – kept in memory only and deleted when you close or reload this tab.
Honest limits
This tool finds the obvious identifiers. It does not understand context: a person can still be recognizable from a job title, a place or a story. Names are detected by salutations, signatures and a first-name list – unusual names or names without such anchors can be missed. Read the result before you send it, and add anything missing manually.
3 texts anonymized so far – counted without content or identifier
Nothing leaves your browser
Detection, replacement and restoration run as JavaScript on your device. Your text is not sent to any server – the only request on use is an anonymous counter ping without content, which you can verify in the network tab of your browser.
Reverse mapping
Placeholders like [PERSON_1] stay consistent across the whole text. Paste the AI answer back and the real names, numbers and addresses are restored – locally.
No model, no download
Patterns, check digits and word lists instead of a machine-learning model. The page loads instantly, works offline once opened, and behaves predictably.
How it works
Three steps – from raw text to a safe prompt and back.
1. Paste & anonymize
Paste your text and click "Anonymize". Personal data is detected and replaced with consistent placeholders such as [PERSON_1] or [IBAN_1].
2. Review & copy
Check the highlighted matches, switch individual ones off, add missing terms – then copy the anonymized text into the AI model of your choice.
3. Restore the answer
Paste the AI answer back. The placeholders are replaced with the original values from the mapping table that never left your browser.
What is detected
Reliable where a checksum or a strict format exists – heuristic where language is involved.
Verified by checksum
IBAN (MOD-97 check), credit card numbers (Luhn), German tax identification numbers (check digit), German social insurance numbers (format).
Strict patterns
Email addresses, URLs, IPv4/IPv6 addresses, phone numbers (German and international formats), dates (12.03.2026, 2026-03-12, 3 March 2026), German street addresses and postal code + city.
Heuristic – please check
Names via salutations ("Dear Ms. …", "Herr Dr. …"), role and kinship words ("our colleague …", "CEO …", "his niece …"), signatures, field labels, a German/English first-name list and first-name/surname pairs mid-sentence (with filters against ordinary noun pairs such as "Deutsche Bahn"); companies via legal forms (GmbH, AG, Ltd., Inc.); German license plates. Once a name is found, its surname and genitive form ("Hitlers") are masked everywhere.
Not detected
Names without any anchor and outside the list, nicknames, indirect identifiers ("the CFO of our Munich office"), non-Latin scripts, content of images or attachments. Add such terms manually.
Typical use cases
Whenever a text is useful for an AI but must not carry real people into it.
Customer emails & support tickets
Let an AI draft a reply or summarize a thread – without handing over the customer's name, address, contract or account numbers.
Contracts & legal texts
Have clauses explained or compared while the parties, IBANs and dates stay on your side.
Applications & HR documents
Structure a CV, prepare interview questions or check a reference letter without exposing the applicant.
Meeting notes & medical letters
Summarize notes or explain a doctor's letter – names and dates of birth become placeholders. Health data deserves extra care (Art. 9 GDPR).
Why anonymize before using AI?
Every text you paste into ChatGPT, Claude, Gemini or another AI model is transmitted to that provider. If it contains personal data – a customer's name, an applicant's address, a patient's date of birth – that is a processing operation under the GDPR, and depending on the provider and settings the data may be stored or used for training. Replacing the identifiers with placeholders before pasting removes the most obvious personal data from the prompt while keeping the text useful. The AI works with [PERSON_1] just as well as with a real name – and you get the real name back at the end.
Anonymization or pseudonymization?
Strictly speaking this is pseudonymization (Art. 4 No. 5 GDPR) from your side: you keep the mapping table and can restore the values. The AI provider never receives that table, so the text it sees contains no direct identifiers. Remaining risk: context can still make a person recognizable – read the result before sending.
Verifiable, not just promised
The detection engine is open source (MIT). Anyone can read how the patterns work, run it locally or improve it. Combined with the network tab – where a click shows only one content-free counter request – "nothing leaves your browser" is something you can check rather than trust.
View the engine source code (MIT)This page describes a technical safeguard and is not legal advice. Whether and how personal data may be processed with AI tools depends on your specific situation – ask your data protection officer or a lawyer.
Frequently asked questions
About AI tools, personal data and what this anonymizer can do.