Anonymize the text of a scanned document before an AI reads it
A scan is a picture: this free tool cannot read it. Run text recognition first, with your scanner's software or your phone, then paste the recognised text below. Names, dates of birth, ID and phone numbers become codes before the text goes to ChatGPT, Claude or Gemini.
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: a reference letter after text recognition
REFERENCE LETTER
To whom it may concern,
I confirm that Ms Ellen Marchbank, born 09/07/1988, was employed by Copperfield Engineering Ltd from March 2019 to August 2025 as a project coordinator. Her National Insurance number is QQ 12 34 56 C.
Ms Marchbamk left on good terms.
Harriet Dunmore, HR Manager, 0161 496 0738REFERENCE LETTER
To whom it may concern,
I confirm that Ms FIRSTNAME-001 NAME-001, born DOB-001, was employed by COMPANY-001 from March 2019 to August 2025 as a project coordinator. Her National Insurance number is ID-001.
Ms NAME-002 left on good terms.
FIRSTNAME-002 NAME-003, HR Manager, PHONE-001Text recognition misread “Marchbank” as “Marchbamk” on one line. Both are coded, but as two different codes: the AI will think there are two people. Fix misspelled names before coding, so each person keeps one code.
What goes wrong with scans, and how to avoid it
Uploading a scan to an AI that reads images sends the whole picture: signatures, stamps, handwriting, an ID photo. Recognising the text yourself and coding it sends only what you choose.
- Get the text. Most scanner apps offer “searchable PDF” or text recognition; phones can copy the text out of a photo. Paste the result in the Text tab.
- Fix names before coding. Recognition errors turn one name into two (see above), and a misread digit can break an ID number into pieces. Read the names and numbers once before pressing Code it.
- Look for what recognition skipped. Handwritten notes, stamps and signatures often do not come out as text. They will not be sent either, but they will not be coded if you later send the image.
The free tool never sees the image itself. The Hidden Tokens app reads scans on your computer, codes the recognised text, and lets you check each page before anything is used; images to redact wait for a human.
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 upload the scan image here?
No. The free tool takes text, Word, Excel and CSV. Recognise the text first, then paste it. The Hidden Tokens app reads scans on your computer.
Are national insurance or ID numbers coded?
Yes, when they keep their usual shape. A recognition error can split a number; check the coded text and add what was missed under Adjust → Also code.
Why does the same person have two codes?
Because the recognised text spelled the name two ways. The engine codes exactly what it reads. Correct the spelling before coding and both lines get the same code.
Is a signature in the scan sent to the AI?
Not if you paste only the text. If you upload the image to an AI, the signature, stamps and handwriting go with 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.