Anonymise, paste into the AI, read back with your real data.
Pasting a document into AI means handing over personal data you no longer control. Tacitum first replaces each piece of data with a generic label ([NAME], [EMAIL], [ADDRESS]…), locally: the document you share becomes irreversible. You paste it into the AI, then you read its answer back with the real names — on your machine only. Nothing is sent, nothing is shared.
All features, free · Windows · 7 formats · no sign-up
All features, free.
10 conversions · all features, scanned documents included · Windows · 100% offline. Leave your email: you'll be the first to know, no commitment and no credit card.
A document that circulates is a leak waiting to happen.
Pasting a contract into ChatGPT, sending a case file to a subcontractor, e-mailing a document. Every time you share personal data, you're on the hook under the GDPR — and the cloud doesn't forgive.
Generative AI
Everyone pastes documents into ChatGPT or Copilot. But your prompts travel to foreign servers: a name, a social security number, an address — and the data is gone for good.
Subcontractors
Sharing an HR, legal or medical file multiplies the copies. Without anonymisation, every recipient becomes a risk.
GDPR fines
Up to 4% of annual turnover. The best protection isn't to encrypt the data — it's to no longer hold it.
Anonymise → the AI → read back. Without sending anything.
ChatGPT, Copilot, Gemini, Mistral… AI works in seconds, but every document you paste into it goes to servers you don't control — and if it contains a name, a patient file or a contract, you remain responsible under the GDPR. Tacitum closes the loop: you mask before, the AI works on safe text, you read its answer back in clear text after.
Anonymise locally
Drag your document into Tacitum. Each piece of personal data becomes a generic label. The resulting file offers no way back to the real values — everything stays on your machine, with no network.
Paste into the AI
The anonymised text keeps all its meaning, but no longer contains a single name, e-mail or identifying number. The answer the AI generates is therefore anonymous too.
Read back in clear text · optional
With Restore mode, Tacitum re-injects your real values into the answer, on your machine: “…to [NAME]” becomes “…to Jane Doe”. This key never leaves your machine, and the shared document stays irreversible.
Your raw document leaves first
- To mask the file, you first have to send it to them in clear text
- Retention, logs, subcontractors: opaque
- A network outage, and the tool stops responding
Nothing leaves. You see everything.
- The raw document never leaves your machine
- Anonymisation and clear-text read-back, locally
- Works even with no internet connection
According to France's data protection authority (the CNIL), anonymisation means making it impossible, in practice, to identify the person, and to do so irreversibly; data anonymised this way falls outside the scope of the GDPR. — Principle stated by the CNIL (paraphrase)
Seven formats. One window.
Drag a file or a whole folder. Tacitum detects, masks and rewrites — preserving the formatting. No blacked-out pages, no broken document. You can even keep certain categories (for example keep the dates).
- .docx Word
- .pdf PDF (text)
- .xlsx Excel
- .doc Older Word*
- .pptx PowerPoint
- .txt Text
- .csv Spreadsheet
* The .doc format requires Microsoft Word installed on the machine. Scanned documents (photos, image PDFs) are supported in the Max edition.
Built for those who can't afford a mistake.
Lawyers & legal teams
Paste pleadings and exhibits into AI without breaching client confidentiality.
Human resources
CVs, contracts, personnel files: anonymised before any sharing or audit.
Healthcare professionals
Work on a patient file without ever exposing their identity.
Public sector
Open data, tenders, letters: publish without risking a leak.
Accountants
Share filings and payslips without handing over your clients' data.
SMEs & DPOs
GDPR compliance with no cloud, no subscription, no IT team.
What people ask us most.
An example transformation. Tacitum replaces each piece of personal data with a generic label; the document you share offers no way back to the real values:
“Jane Doe” becomes [NAME], “14 Lilac Street, London” becomes [ADDRESS],
“j.doe@email.com” becomes [EMAIL], “+44 20 0000 0000” becomes [PHONE],
a national ID number becomes [ID] and “Doe Motors Ltd” becomes [COMPANY].
Why the name “Tacitum”?
“Tacitum” comes from the Latin tacitus — “silent”, “left unsaid”. It is the root of the English word tacit (a tacit agreement, what goes without saying) and the name of the Roman historian Tacitus, famous for his concision. The software's whole purpose fits in that word: once processed, the document falls silent — in the file you share, each piece of personal data becomes a generic label and no table remains.
Can I use ChatGPT or Copilot with my documents without breaching the GDPR?
Yes, provided you anonymise the document before pasting it. Everything you send to a generative AI (ChatGPT, Copilot, Gemini, Mistral…) goes to servers you don't control: if it contains personal data, that is a transfer subject to the GDPR, and the responsibility remains yours. Tacitum replaces each piece of data locally with a typed, irreversible label. The text keeps all its meaning for the AI, but no longer contains anything identifying — you keep the speed, without the leak.
Is Tacitum really offline?
Yes. Tacitum runs 100% locally on your Windows machine: no file and no data is ever sent over the Internet, no API, no account, no network connection. It works even with no internet connection.
Can I recover the original values? Does Restore mode make the document reversible?
By default, no: the document you share offers no way back to the real values — anonymisation is irreversible for whoever receives it. Tacitum offers an optional “Restore mode”, off by default. If you enable it, an encrypted table is kept on your machine only (tied to your Windows account), automatically wiped and never shared. It lets you recover your values locally and read the AI's answer back with the real names. This table concerns only you and changes nothing about the shared document, which stays anonymous and impossible to re-identify — for the recipient as for the AI.
Which formats are supported?
Seven formats: .docx, .pdf (text, not scanned images), .xlsx, .doc (requires Microsoft Word installed), .pptx, .txt and .csv. You can process several files, or a whole folder, at once.
How much does it cost?
10 free conversions, no sign-up. Beyond that, a perpetual licence at €79 per seat: a one-time payment, no subscription. Invoice provided, updates to the purchased version included, multi-seat pricing on request.
Try first. Pay once.
Start with 10 free conversions, no sign-up and no credit card. Then a one-time payment, no subscription and no cloud to pay for every month.
- All 7 formats: .docx, .pdf, .xlsx, .doc, .pptx, .txt, .csv
- Multiple files (or a whole folder) at once, formatting preserved
- 100% offline, no data transmitted
- Updates to the purchased version included
- Everything in Perpetual, plus:
- Scanned documents: photos and image PDFs, read then anonymised
- Priority support by e-mail
- Early access to new features
- Multi-seat deployment & site licences
- AI tools & workflow automation integration
- Multi-file automation & internal workflows
- Dedicated support & tailored terms
No commitment · one-time payment · no card required for the trial · multi-seat pricing on request