Word, Excel, PowerPoint
Plus OpenDocument, RTF and plain text. It reads the content, not just what shows on screen.
The same key you use on text.
For lawyers, tax advisers and medical clinics.
Mac with Apple silicon and macOS 14 or later · Windows 10 or later, 64-bit (x64) · under 2 MB.
The first time you open Nonimo, Windows may show a SmartScreen notice because the app is new: click “More info”, then “Run anyway”.
Keep client data private. Names, IDs and case numbers become placeholders before you paste, and come back in the reply.
Select any text, press one key. Works with ChatGPT, Claude, Copilot and any other app.
Below is exactly what Nonimo returned on three made-up documents. Every name, ID number, account and address was invented for this page and belongs to nobody.
This is a recording, not a live demo: Nonimo runs on your own computer, not in a browser tab. How to check what Nonimo sends →
A whole conversation, caught at the exact moment it crosses your computer.
Hi, can you help me with a client file?
Of course. Paste what you have.
The client is Rachel Hartley, Medicare 2000 00002 1. She wants a written estimate before Friday on claim CLM-2026-88142. The client is [PERSON_1], Medicare [MEDICARE_1]. She wants a written estimate before Friday on claim [REFERENCE_1].
On the way out, the names, the Medicare number and the claim reference all stayed here.
Claim [REFERENCE_1] is still open, so [PERSON_1] is well within time to ask for it in writing. Claim CLM-2026-88142 is still open, so Rachel Hartley is well within time to ask for it in writing.
On the way back, they return. And not just the name: the AI answered with all three labels and never knew whose they were.
Good. Can you draft the email? Put her Medicare number in the reference line and address it to the assessor, Daniel Okonkwo. Good. Can you draft the email? Put her Medicare number in the reference line and address it to the assessor, [PERSON_2].
Here is the draft for [PERSON_1], addressed to [PERSON_2]. I put Medicare [MEDICARE_1] in the reference line, as you asked. Here is the draft for Rachel Hartley, addressed to Daniel Okonkwo. I put Medicare 2000 00002 1 in the reference line, as you asked.
You paste the name ONCE. For the rest of the conversation Nonimo already knows who [PERSON_1] is, and puts it back without being told again.
The identifiers come built in, and so do names and addresses. On top of that, you add your own terms.
When a number’s own check digit adds up, it is replaced straight away, without asking you.
Picked up where documents put them: a form field, a signature, the title before a surname. An unusual surname is treated the same as a common one.
The claim number, the case file, the policy: the numbers that pull up a whole person if they leak.
Click the document and press your key: its text comes out masked, ready to paste into the chat, and you don't even open it. Drop it on the Nonimo window instead, or on its Dock icon on a Mac, and you also get a masked copy next to the original.
Plus OpenDocument, RTF and plain text. It reads the content, not just what shows on screen.
The same key you use on text.
Including the ones produced by typesetting software.
A file saved with the wrong extension is still read.
The masked text is copied, ready to paste. Drop the file on the window and a masked copy appears next to the original: Word comes back as Word, a PDF as a new PDF with just the text, anything else as text.
The original file is not touched.
The file is read where it sits. It is not uploaded anywhere to be processed — not to us, not to anyone.
And it works with no connection.
The originals stay on your computer, and not a word of your text reaches us. How to check.
The same text always gives the same result, in a fraction of a second.
Nationality, ethnicity or language are often the point of the question — in a protection claim, they are the case. Nonimo masks who the person is, not what the question is about.
Anything short of certain is replaced on screen, with the reason beside it, and one click undoes it.
Extension deployed by policy, a compliance panel installed on your own server, and the monthly report an auditor asks for.
What gets covered and why, sector by sector.
Where the EU AI Act reaches beyond Europe, and when a paste into ChatGPT becomes a breach you have to report.
Nonimo is a desktop application for Mac and Windows that masks the personal data in a piece of text before you paste it into ChatGPT, Claude, Copilot or Gemini. You select the text, press one key, and names, ID numbers, IBANs and matter numbers come back replaced by labels. No account is needed, and your clients’ data stays on your computer.
Pseudonymization in Nonimo is reversible: the mapping between each label and its real value is stored encrypted on your own computer and travels nowhere. To recover the original text you copy the answer from the AI and press the same key, and the names go back into place. That mapping is kept for as long as you keep using the conversation, with a thirty-day inactivity limit.
Pseudonymization replaces each piece of personal data with a label while the mapping is kept somewhere, so the text can be read in full again. Anonymization breaks that mapping for good, and then there is no way back. Nonimo pseudonymizes: the AI sees the label and you get the name back when you read the answer. That is why pseudonymized text is still personal data for whoever holds the table: that table is the additional information of article 4(5) of the GDPR.
Nonimo helps a firm meet its GDPR obligations, but it does not meet them on the firm's behalf. Pseudonymization is one of the technical measures the GDPR names in Articles 25 and 32(1)(a), and taking identifiers out before a paste cuts what reaches the AI provider, in line with data minimization under Article 5(1)(c). The firm still needs a lawful basis, a processing contract with the provider and clear information for its clients, and pseudonymized text is still personal data for whoever holds the table that reverses it.
Is putting client data in ChatGPT a data breach, and must you tell?
Nonimo opens the whole document: Word, Excel, PowerPoint, OpenDocument, RTF, PDF and plain text. It reads the contents of the file, not just what is visible on screen, and masks the personal data it finds inside. Drop the document on the Nonimo window and you get its masked text, copied and ready to paste, plus a masked copy next to the original: a Word file comes back as the same Word file, a .txt, .csv or .md file as the same text, and a PDF as a new PDF with just the text. From Excel, PowerPoint, OpenDocument and RTF you get the text alone. Images go through as they are: a scanned PDF is made of images, and Nonimo does not read it. On Windows, a PDF in letters outside the Western European alphabet, such as Polish, Czech, Greek or Cyrillic, comes back as text only.
Nonimo costs nothing to use. It masks up to 200,000 words a month without asking for a card or an account, and if that falls short, a licence that also costs nothing, valid until 31 January 2027, lifts the limit.
Nonimo stops masking until the next month. To lift the limit you leave an email address on the licence page at nonimo.ai and a free licence file is sent to you. It is not a payment, there is no account and no password: the file is checked on your own computer.
The 200,000 words a month that Nonimo allows are plenty for normal, moderate use, although a firm working through a large volume of documents can reach the limit. The counter includes both directions, masking the text on the way out and restoring it in the reply, so in practice the allowance covers about 100,000 words of your own: at around 500 words a page, roughly two hundred pages a month. If that falls short, you can request a licence that lifts the limit until 31 January 2027, and like the app it costs nothing.
Nonimo does not use an artificial intelligence model to detect the data. The same text always gives the same result, and nothing is left to chance.
Nonimo sends none of your text anywhere: the originals stay on your computer, and not a word of it reaches us. What you paste into the AI tool is the masked version. The security page at nonimo.ai explains how to check this for yourself.
Nonimo has no sign-up and no password, and the application never asks for an email address. The only place on the whole website that asks for one is the licence page, and only if you are lifting the monthly word limit.
Nonimo works with every AI tool, because it connects to none of them. It works on the text you select on your own computer before you paste it, so it behaves the same with ChatGPT, Claude, Copilot, Gemini or any other site. It is not an extension for one particular tool and it needs no integration.
Nonimo keeps masking without an internet connection, and it does not depend on our server being up.