AI checks inside Word, Excel, PowerPoint and Outlook, without leaking the details.

What every add-in does

Check reads the whole file, or only what you selected, with the same rules as the site’s own tools:

• Phrases that sound machine-made. Filler openings such as "Certainly", AI-favorite words such as delve and seamless, long dashes and the other habits readers notice, as the Robot-Speak Checker finds them.
• Claims to check. Every sentence or cell with a number, a date, a quote or a named source, riskiest first, because these are the details AI makes up most often. The same rules as the Fact Check List.
• Markdown and blanks. Stars and pound signs left over from a chat, and text such as [insert company name] that is easy to miss on page 9 or in row 400.
• Private details. Email addresses, phone, card, bank and account numbers, so nothing goes out by mistake.

Safe for AI swaps every name, email address, phone and account number for a placeholder such as [NAME_1], the way Safe Paste does. You say what the AI should do, open ChatGPT or Claude with the text, then paste the answer back into the pane, and the real details go back in. Prompt scores a request you drafted out of 10 on the ten checks, and rebuilds it with the missing parts as blanks, as the Prompt Improver does.

Word: check a draft before it goes out

Press Check draft on the Home tab. Click a finding and Word selects the phrase; Highlight all marks every finding in yellow, and Clear highlights takes the marks away again. Many people draft their prompts in a document first: select one and open Prompt to score it where you wrote it. When Safe for AI brings an answer back, one press puts it in the document where your cursor is.

Download the Word add-in file

Excel: ask AI about a table without handing it over

A customer list or an aged debt report is exactly what people want help with, and exactly what should not be pasted into a chat. Press Safe for AI on the Home tab:

1. Choose Use the selection, or Use the whole sheet. The pane lists every name, email address, phone, card and account number it found, each with the placeholder it will use. Untick any that can stay.
2. Say what you want, for example "which customers are more than 60 days late, and how much do they owe in all?", and open ChatGPT or Claude with the table in it. The AI sees [NAME_1] and [EMAIL_1], never the real details.
3. Paste the answer back and press Put the details back, then Put it in a new sheet. The answer goes into a sheet of its own, with a table split into columns, so your own cells are never overwritten. Anything Excel would run as a formula goes in as plain text.

Check also reads AI-written text in cells, such as product descriptions or ad lines one per row, up to 20,000 cells at a time; click a finding and Excel selects its cell. Teams that keep their prompts in a spreadsheet can select one and open Prompt.

Download the Excel add-in file

PowerPoint: check every slide before the room reads it

A deck drafted with AI tends to show it on the slide everyone reads at once, and a wrong figure on a slide is the one people remember. Check reads text boxes and placeholders across the presentation; click a finding and PowerPoint goes to its slide and selects the words. Tables, speaker notes, grouped shapes and text inside pictures are left out. Reading every slide at once needs PowerPoint from mid-2022 or later (on a Mac, version 16.62 or later); older versions check the text you select.

Safe for AI works slide by slide, for example "make each slide shorter and clearer for the leadership team", and Put it on the slide replaces the selected text, or adds a text box when nothing is selected.

Download the PowerPoint add-in file

Outlook: reply with AI without sending it who wrote to you

1. Open the email and press Reply with AI.
2. Write what you want to say in a few words, such as "yes to Tuesday, but ask for the budget first", and pick a tone.
3. Press ChatGPT or Claude. It opens with the request ready, and the email in it has the sender and every name, email address, phone and account number replaced by a placeholder. See what the AI will get shows exactly what leaves the pane.
4. Paste the draft back and press Reply with this draft. Outlook opens a reply with the real names and numbers back in, for you to read and send.

In a new email or a reply, Check draft reads what you wrote before you send it, including addresses and numbers that may not be meant for this reader.

Download the Outlook add-in file

How to add it

Until the add-ins are listed in Microsoft AppSource, each Office app adds one from a small file that tells it where the add-in lives: download the file for your app from its section above.

1. Word, Excel or PowerPoint: open a file in the app on the web, at office.com. On the Home tab choose Add-ins, then More Add-ins. Choose My Add-ins, then Upload My Add-in, and pick the file. Check draft, or Check and Safe for AI, appear on the Home tab.
2. Outlook: in Outlook on the web or the new Outlook for Windows, open an email and choose Apps or the menu with three dots, then Get Add-ins. Choose My add-ins, then under Custom add-ins choose Add a custom add-in, then Add from file. Outlook on Windows and Mac usually picks it up from the same account.

The wording can differ slightly between versions. At work, your IT team can add any of them for everyone at once from the Microsoft 365 admin center (Settings, Integrated apps, Upload custom apps) with the same file, which is also how they reach the desktop apps before the AppSource listing. Some workplaces turn off custom add-ins; there, the admin center is the way.

Private by design

Every check runs in the pane, inside the Office app. The add-ins send nothing you write to thinkhard.si or anyone else and store nothing. They read the file only when you press a button, and change it only when you ask, such as a highlight you can clear or a new sheet for an answer. Text goes to ChatGPT or Claude only when you press their button, with placeholders in place of the details you kept ticked. The full detail is in the privacy policy.