Anonymise, prompt the AI, read it back in clear: the full loop.
Five minutes is all it takes. This guide follows the real way Tacitum is used: from dropping in your document to reading the AI's answer back with your real data — without your real data ever leaving your machine.
Before you start: install Tacitum
Download and install
Two ways to install Tacitum on Windows 10 or 11 (64-bit) — it is the same application, with the same features:
From the Microsoft Store — open the Tacitum listing on the Microsoft Store and click Get: Windows downloads and installs everything for you, with no security warning.
Or by direct download — grab Tacitum for Windows: a digitally signed .exe installer of about 20 MB. Run it — it downloads the application (≈ 600 MB, analysis engine included) during setup and lets you pick the language, the theme, and how long local mappings are kept. This is the route to take if the Store is disabled on your machine, as it is in some companies.
Either way, those settings stay adjustable at any time in Settings.
You start with 10 free conversions, every anonymisation feature included: no account, no sign-up, no credit card.
Step 1 — Anonymise a document
Drop in your files
On the Anonymize page, drag one or more files — or a whole folder — into the drop zone, or click to browse. Seven formats are supported (.docx, .pdf, .xlsx, .doc, .pptx, .txt, .csv) plus scanned documents and photos, read automatically by text recognition.
Choose your options
Three options sit above the convert button:
Restorable mode (on by default) — keeps, on your machine only and encrypted, what you need to recover your values and read the AI's answer back in clear. It changes nothing about the file you produce, which stays irreversible for whoever receives it.
Remove metadata — strips author, comments, hidden properties from the file.
Remove images — an image can hold readable data (a signature, a stamp, a header): they are removed and replaced with a marker.
The "Choose the data to keep unmasked" link lets you keep some categories in clear — for example keeping dates if your analysis needs them.
Run the conversion
Two buttons, two uses: "Anonymise and review…" first shows the list of detected data for validation (recommended, see step 2); "Convert" anonymises and writes the file straight away.
The result is written next to the original, which is never modified. The output file name is anonymised too (a Letter_John_Smith.docx becomes Letter_[NOM]_anonymise.docx) and, for a folder, everything is grouped in a Tacitum_anonymise_… folder.
A real document, before and after
Here is a real Word letter — header with a logo, formatted tables, a stamp and a signature — put through Tacitum. On the left the original, on the right the file it produces:
[IMAGE SUPPRIMEE]. No blacked-out page, no broken document.Step 2 — Review before writing
With "Anonymise and review…", Tacitum shows the full list of detected data before producing the file. You stay in control:
Validate, keep, add
Each detection appears in a table with its type and a preview of the result. You can keep a value that was flagged by mistake (for this file, or permanently via your saved lists), or on the contrary mask a term you select in the preview — once, or for good.
The preview updates live: what you see is exactly what will be written.
Step 3 — Use the document with the AI of your choice
ChatGPT, Claude, Copilot, Gemini, Mistral…
Send the anonymised document to your usual AI, exactly as you normally would: summary, analysis, translation, drafting. The text keeps all its meaning — the AI understands that [NOM-A2H7KQ] refers to the same person throughout — but no longer contains any identifying data.
Only that anonymised state crosses the Internet. The file you produce carries no lookup table: it is irreversible for whoever receives it, the AI included.
For a simple e-mail or a snippet to paste, the Anonymize text page does the same thing without a file: paste, anonymise, copy the result.
Step 4 — Read the answer back in clear, on your machine
"Recover my values"
The AI answers using the same labels. Paste its reply into the Recover my values page: Tacitum re-injects your real data and you read the text with the real names — without anything going back over the Internet.
This works thanks to Restorable mode: a mapping kept on your machine only, encrypted and tied to your Windows account, automatically wiped after the period you chose (30 days by default), and never shared or transmitted. It concerns only you: the shared document itself stays irreversible.
Optional — the AI Connector: Claude Desktop or Codex Desktop reads your anonymised documents, no copy-paste
With the AI Connector (included in the free trial, then €69 for one year, no subscription; no VAT applicable, art. 293 B CGI), Claude Desktop or Codex Desktop asks Tacitum for the document itself. Nothing to copy or attach: you pick the file, or a whole folder, in Tacitum's file picker, you review the masked data in the usual window, and only the anonymised text goes to the assistant. Its answer is read back in clear in a local window, and can become a Word document with your real values, created on your machine.
The cycle, without leaving the conversation
"Analyse my contract with Tacitum" → Tacitum opens its file picker → local analysis and review → "Confirm and send to Claude" (or "… to Codex") → the assistant answers with the labels → "Show me your answer in clear with Tacitum".
The assistant never receives the original file, its name in clear or your real values; for the assistant, as for any recipient, the text is irreversible. The AI Connector is in Tacitum (left column → AI Connector…): try it for free with the 10 trial conversions, then add it to the Tacitum licence.
What Tacitum detects
Each value is replaced by a typed label, consistent throughout the document: the same person keeps the same code everywhere. The main categories:
| Label | Category | Examples |
|---|---|---|
| [NOM] | People's names | surnames, first names, including in CAPITALS or in signatures |
| [EMAIL] | E-mail addresses | work and personal |
| [TÉLÉPHONE] | Phone numbers | landline, mobile, French and international formats |
| [ADRESSE] | Postal addresses / places | number and street, postcode and city, places |
| [SOCIÉTÉ] | Company names | companies, firms, organisations |
| [DATE] | Dates | birth, hire, deadlines (can be kept if you choose) |
| [N SECU]… | Administrative IDs | social security number, company registration, ID card, passport, plates |
| [IBAN]… | Bank details | IBAN, bank details, card numbers |
| [CONFIDENTIEL] | Your own terms | any term added to your deny list — always masked |
[NOM], [SOCIÉTÉ]…) for French and English documents, Spanish, German or Italian wording with the language pack (see below).Documents in Spanish, German or Italian
French and English are included in Tacitum. For Spanish, German and Italian, Tacitum adds the language pack — the analysis model for that language, free, downloaded once (a few dozen MB) — then analyses those documents like any other, entirely on your machine.
Install a language pack
Open Settings… → Document languages and click Download next to the language. Tacitum also offers it on its own: Install the pack when it recognises a document in a language that is not installed, Download the pack at first launch if its interface is in Spanish, German or Italian. Nothing is downloaded without your click, and a pack never updates itself. Without the pack, Analyse anyway processes the document as French, with less reliable detection (degraded mode).
The download is a plain request to Tacitum's update server, with no document, licence key or device identifier: the server only sees your IP address, as with any connection (see the privacy policy, section 2.j, in French). The same screen lets you update the pack (Update) or remove it (Remove).
Regions and identifiers recognised
The language and region of each document are recognised automatically (Document region → Automatic, adjustable if needed). On top of names, addresses, e-mails, phone numbers, bank details and dates, each pack recognises its countries' identifiers:
| Country | Identifiers recognised (examples) |
|---|---|
| Spanish pack | |
| Spain | DNI, NIE, NIF / CIF, social security number (NUSS), cadastral reference |
| Mexico | CURP, RFC, INE |
| Argentina | CUIT, DNI |
| Colombia | NIT, cédula |
| Chile | RUT |
| German pack | |
| Germany | Steuer-ID, Steuernummer, SV-Nummer, KV-Nummer, Personalausweis, Reisepass, Handelsregister (HRB…), USt-IdNr, number plates, Aktenzeichen |
| Austria | SV-Nummer, Firmenbuchnummer (FN), UID |
| Switzerland | AHV-Nummer, UID (CHE-…) |
| Italian pack | |
| Italy | codice fiscale, partita IVA, licence plate (targa) |
| Italian-speaking Switzerland | AVS number, IDI (CHE-…) |
Labels in the document's language
A Spanish document gets Spanish labels, a German document German labels, an Italian document Italian labels; a French or English document keeps the French labels. Nothing else changes: same code for the same value, Restorable mode, irreversible shared document.
| French | Spanish | German | Italian |
|---|---|---|---|
| [PRÉNOM] [NOM] | [NOMBRE] [APELLIDO] | [VORNAME] [NAME] | [NOME] [COGNOME] |
| [EMAIL] | [CORREO] | [E MAIL] | [EMAIL] |
| [TÉLÉPHONE] | [TELÉFONO] | [TELEFON] | [TELEFONO] |
| [ADRESSE] | [DIRECCIÓN] | [ADRESSE] | [INDIRIZZO] |
| [SOCIÉTÉ] | [EMPRESA] | [FIRMA] | [AZIENDA] |
| [DATE] | [FECHA] | [DATUM] | [DATA] |
| [N SECU] | [NSS] | [SV NUMMER] | [CODICE FISCALE] |
| [CONFIDENTIEL] | [CONFIDENCIAL] | [VERTRAULICH] | [RISERVATO] |
Going further
A whole folder at once
Drop a folder: Tacitum offers to include the subfolders, processes everything in one pass and groups the results in Tacitum_anonymise_…, keeping the tree structure if you want. Masking is consistent across the whole batch: a person cited in several files gets the same code everywhere.
Scanned documents and photos
Scanned PDFs and images (.png, .jpg…) are detected and read automatically, then anonymised to .txt — all locally. The quality of the result depends on the scan; difficult documents are explicitly flagged for re-reading.
Anonymise a plain text
The "Anonymize text" page handles an e-mail or a pasted passage, without creating a file: paste, click, copy the result to your AI. The answer is then restored in "Recover my values", just like a document.
Your settings, once and for all
In "Settings": interface language (French, English, Spanish, German or Italian), document languages (Spanish, German and Italian packs, see above), document region (automatic, France, Quebec / Canada or a pack country), dark or light theme, how long local mappings are kept, export/import of your permanent lists to move them to another machine.
Activate your licence
After purchase: two minutes
After your online purchase (€79, one-time payment, no VAT applicable, art. 293 B CGI), your licence key arrives immediately by e-mail, with your invoice. In Tacitum, click "Enter a licence", paste the key, confirm: done.
Activation needs a brief internet connection (only the key and a technical fingerprint of your Windows session are checked — never your documents, which never leave your machine under any circumstances). One licence covers one user, i.e. one Windows session.
Want to go further with Claude Desktop or Codex Desktop? The AI Connector can be tried for free during the trial, then added to your licence (€69 for one year, no subscription), from inside Tacitum.
This guide is also available as a printable file: quick-start guide (PDF). A problem, a question? Write to us: contact@tacitum.tools.
Ready to try? It's free.
10 free conversions, every anonymisation feature included — no account, no credit card.