Pseudonymize a data sample before developers or an AI coding assistant see it
Drop a CSV or Excel sample taken from production. Names, emails, IBANs and other identifiers become codes, consistently across rows; IDs, dates and plan values stay readable. Share the coded sample in a ticket, or paste it into ChatGPT, Claude or Copilot to write the import script or reproduce a bug.
Restoring uses the key of this tab: code your text here first, keep this tab open, then come back with the answer.
Adjust
See the key (it stays in this tab)
The key links each code to the real value. It exists only in this tab's memory: close or reload the tab and it is gone.
connect-src 'none' in its security policy) and loads no analytics. Turn Wi-Fi off once the page has loaded: the tool works just the same. The engine is the one inside the Hidden Tokens app.How it works
1 · Code
Paste a text or drop a file. Names, companies, addresses, emails, phone numbers, bank details, ID and case numbers become codes such as NAME-001 or COMPANY-001. Unknown proper nouns are coded too: when in doubt, the engine codes.
2 · Send the codes
Copy the coded text, or download the coded file, and give it to ChatGPT, Claude, Gemini or Copilot. The AI reasons on the codes: it still knows who did what, not who they are.
3 · Restore
Paste the AI's answer in the Restore tab, in the same browser tab. The codes become the real names again, on your screen only.
Example: two rows of a users table
id,first_name,last_name,email,iban,created_at,plan
1001,Hugo,Banfield,hugo.banfield@example.com,GB33BUKB20201555555555,2025-01-14,pro
1002,Isla,Holloway,isla.holloway@example.net,GB94BARC10201530093459,2025-02-03,freeid,first_name,last_name,email,iban,created_at,plan
1001,FIRSTNAME-001,NAME-001,EMAIL-001,IBAN-001,2025-01-14,pro
1002,NAME-002,NAME-003,EMAIL-002,IBAN-002,2025-02-03,freeNames, emails and IBANs are coded, consistently: the same customer would keep the same code in every row. Row IDs, dates and plan values stay readable, so the AI can still reason about the schema and the bug.
Coded samples are for reading, not for seeding a database
The quickest way to get help with a data bug is to paste a few real rows into an AI or a ticket. Those rows are customers. Coding them keeps the shape of the problem and removes the people.
- Good for: showing an AI coding assistant the columns and a few rows, reproducing a parsing bug, writing a transformation, sharing a sample with a contractor.
- Not a fake-data generator:
EMAIL-001is not a valid email address andIBAN-001will fail a checksum. If your test environment validates formats, generate synthetic data instead. - Check every column. The engine codes what it recognises as identifying and, when in doubt, codes. A surname that is also a common word or a place name can stay readable: scan the result, and add any value under Adjust → Also code.
The free tool takes up to 1,000 rows per file, with a new key for each file, so codes do not match across tables. To pseudonymise several related exports with one key, use the Hidden Tokens app.
The free tool or the Hidden Tokens app?
This free tool
- One text or one file at a time
- Up to 3,000 words or 1,000 spreadsheet rows
- The key lives in this tab and disappears when you close it
- Word, Excel, CSV and text
The Hidden Tokens app
- Whole folders: the same person keeps the same code in every document
- One key per case file, kept on your computer
- PDF and scanned documents, read on your computer
- Inside Claude Desktop, and in ChatGPT, Gemini and Copilot with the extension
- Industry packs, firm rules and a signed proof of what the AI saw
A word on the word “anonymize”
Strictly speaking, this tool pseudonymizes: each value is replaced by a code that can be reversed with the key. Under the GDPR, pseudonymised data is still personal data for whoever holds the key, which here is you, in this tab. What the AI receives no longer names anyone directly. Clues can remain, such as a job, a town and an age together: the tool warns you when it sees them. Read the result before sending it.
Questions
Can I load the coded file into my test database?
You can, but formats break: codes are not valid emails, IBANs or phone numbers. Use the coded sample to read and reason about, and synthetic data for automated tests.
Are foreign keys preserved?
Within one file, the same value always gets the same code. Across files, no: each file starts a new key. The Hidden Tokens app keeps one key across files.
What about SQL dumps?
Paste the INSERT lines you need into the Text tab, up to 3,000 words. Values in quotes are coded like any other text; check the result.
Is a pseudonymised sample still personal data?
For whoever holds the key, yes. Here the key stays in your browser tab; the people you share the coded sample with cannot reverse it.
Other ways to use the free tool
By file type
By AI tool
By task
For whole folders, use the app
Hidden Tokens codes whole case files on your computer with one key, works inside Claude Desktop and in your browser, reads PDFs and scans, and puts the real names back into Word and Excel files.