AI add-ins for Microsoft Word: 9 compared

Every tool here installs into Word as a task pane beside your document. What each one does to the text, which need a paid Microsoft licence, and the one job almost none of them can do.

Almost every AI add-in for Word is a writing assistant. It reads the words in front of it and gives you different words back — shorter, clearer, more formal, translated, proofread. That is a genuinely useful category and it is very crowded. What it is not is the job most business documents actually need, which is getting the right numbers into the document and keeping them right next month. This page sorts the list by that distinction, because it is the one that decides whether a tool will help you.

If you are on the Google side of the fence, the sister directories cover AI add-ons for Google Docs and AI for Google Sheets. For the spreadsheet equivalent of this page, see AI add-ins for Excel.

Fair warning: Quiriz is ours, and it is in this list. I have said plainly where the others beat us rather than pretend they do not — for most writing jobs, several of them are the better buy. Availability and capability claims come from each vendor's own AppSource listing or documentation, checked September 2026. Pricing in this category changes constantly, so confirm before you buy rather than trusting any roundup, including this one.

The three jobs an add-in can do

Buying the wrong kind is the most common mistake in this category, and the listings do not make the distinction clear:

• Improve the words you already wrote. Proofread, rewrite, shorten, change tone, translate. Grammarly is the archetype. Cheap, reliable, narrow.
• Write new text from a prompt. Draft a section, expand a bullet, summarise the document. Copilot, Claude and the ChatGPT panes all do this. The quality now depends mostly on the model behind it, which is why these products are hard to tell apart.
• Put real data in the document. A number, a table or a chart from your own systems, with the ability to update it later. Almost nothing in this category does this, and it is what a monthly report or a client update is made of.

Jobs 1 and 2 are about the text. Job 3 is about the facts. An add-in that is excellent at the first two can still leave you exporting a spreadsheet, building a chart, pasting it in, and typing the total into a sentence by hand.

Quick comparison table

"Brings in your data" means values from outside the document — a spreadsheet, a database, a business system — placed in the document as something that can be updated later, rather than pasted once.

Microsoft 365 Copilot

The job: draft, rewrite, summarise, and pull context from your own Microsoft 365 content.

Copilot is the deepest integration available, for the obvious reason that Microsoft wrote both halves. It sits in the Word ribbon rather than in a bolted-on pane, it can draft from a prompt, rewrite a selection, summarise a long document, and — the part no third party can match — reference your other files, meetings and email through Microsoft Graph. "Draft a status update based on last week's project notes" is a real Copilot instruction and not a real anything-else instruction.

Where it stops: it is a licence on top of a licence, and it is per-user, which makes it an expensive default for a small team where two people write the documents. On the data question it is better than the writing assistants and still not a reporting tool: it can find the spreadsheet and quote from it, but it does not compute a metric across your datasets, draw a chart from the result, and let you refresh both next month.

Pick it if your organisation is already all-in on Microsoft 365 and you want one AI that spans Word, Excel, Outlook and Teams.

Claude for Word

The job: a serious writing and editing assistant with a long context window.

Anthropic ships first-party add-ins for Word, Excel, PowerPoint and Outlook. The Word one runs as a task pane that reads the open document, so it can draft new sections in the voice of what is already there, review a contract, restructure an argument, or scan a long document for inconsistencies. Long-document work is where it is strongest — it holds far more of the text at once than a copy-paste workflow ever manages.

Where it stops: it works with the document, not with your systems. It requires a paid Claude plan. And as with every general assistant, it will happily discuss the numbers you wrote without any way of knowing whether they are right.

Pick it if your documents are mostly prose and the hard part is the writing.

Grammarly

The job: grammar, spelling, clarity and tone.

The oldest and by some distance the most-installed add-in in this list, and still the one most people should have. It has grown generative features, but the reason to install it has not changed: it catches the things you stop being able to see in your own writing after the third read. The free tier is genuinely useful rather than a demo.

Where it stops: it is about sentences. It has no view of your data and no interest in whether a claim is true.

Pick it if you want one thing that quietly improves everything you write, forever.

Quiriz for Word

The job: put answers from your own data into the document, and refresh them next month.

This is ours, so read it with that in mind. Quiriz for Word is not a writing assistant — it is built for the recurring report. You type a question where its answer belongs, select it, and press Chart, Table, Figure or Notes. The answer replaces the words that asked for it: tables come in as real Word tables captioned in Word's Caption style, and a Figure is one number set inside your own sentence with the surrounding words untouched.

You can also write the whole document before the data exists, leaving markers such as =QUIRIZ.ASK("net sales by month", "chart") where answers go, then press Resolve markers to answer them all in one pass. The spelling matches =QUIRIZ.ASK() in Quiriz for Excel, so a formula copied out of a workbook means the same thing in the document.

The point of all that is the month after. Every chart, table, figure and commentary remembers the question behind it, so Refresh all asks every question again against the new data: the charts gain their new months, the totals inside your sentences move, and your headings, numbering, column widths and prose stay where they were. Turn on tracked changes for refreshes and Word shows each figure that moved as a revision to accept or reject.

Where it stops, honestly: it will not improve your writing. It has no proofreader, no tone control and no draft-me-a-section button, and if what you need is better prose then Grammarly or Claude is the better purchase. It also needs your data in Quiriz first — uploaded, or appended from a connected folder — which is real setup work that pays back only if the document recurs. For a one-off memo it is the wrong tool.

Pick it if you produce the same report every month and the tedious part is the numbers, not the words.

GPTLocalhost

The job: the same drafting and rewriting, with the model running on your own machine.

An unusual and genuinely differentiated option: it connects Word to a locally-hosted model rather than a cloud API, so document text never leaves the computer. For regulated work, client-confidential drafting, or anywhere a cloud AI is simply not permitted, that is the whole argument, and no amount of vendor privacy policy substitutes for it.

Where it stops: you are responsible for running the model, and local models are usually smaller and slower than the frontier ones behind the other add-ins here.

Pick it if the text cannot leave your machine.

AI Perfect Assistant

The job: a library of ready-made prompts across the whole Office suite.

Rather than a chat box, it offers dozens of prepared actions — rewrite this formally, summarise, generate a reply, expand these bullets — and covers Word, PowerPoint, Excel and Outlook from one purchase. The prompt library is the product: it is for people who know what they want done but do not want to write the instruction each time.

Where it stops: breadth over depth, and the same data blindness as every writing assistant here.

Pick it if you want one AI helper across several Office apps and prefer buttons to prompts.

Ghostwriter and the ChatGPT panes

The job: ChatGPT, in a pane, beside your document.

A cluster of products — Ghostwriter was among the earliest, and several more have followed — that put an OpenAI model in a Word task pane so you can draft, expand, rewrite or check a selection without switching windows. They differ mainly in interface, pricing model and whether you supply your own API key.

Where it stops: honestly, these are convenience wrappers. If you are disciplined about copy and paste you already have most of this free in a browser tab. The value is the friction removed, which for some people is worth real money and for others is not.

Pick one if you use ChatGPT constantly while writing and the window-switching is what annoys you.

Zotero and Mendeley (not AI, but worth knowing)

Both install Word add-ins that manage citations and build a bibliography as you write. Neither is an AI tool, and both are on this page because they are consistently the answer to "what should I install in Word" for anyone writing academic or research documents — a question the AI roundups keep answering badly.

How to install an add-in in Word

1. Open Word and go to the Home tab. Click Add-ins. On some versions it is Insert → Get Add-ins.
2. Search AppSource by name and click Add.
3. The add-in appears as a button on the ribbon and opens a task pane beside the document.

Two things that trip people up. On a work computer, your administrator may have turned the store off entirely, in which case add-ins have to be deployed centrally through the Microsoft 365 admin centre and nothing you do in Word will help. And an add-in installed on Windows follows your account to Word on the web and on Mac, because modern Office add-ins are web apps rather than installed programs.

Which should you pick?

• You want better writing. Grammarly, free tier first. Add Claude for Word if you work on long documents and the drafting itself is the effort.
• Your company is deep in Microsoft 365. Copilot, if the per-user cost clears for the number of people who actually write documents.
• The text cannot leave your machine. GPTLocalhost.
• You want one helper across Word, Excel, PowerPoint and Outlook. AI Perfect Assistant, or Copilot if budget allows.
• You rebuild the same report every month and the numbers are the problem. Quiriz for Word — and note this is a different purchase from all of the above, not a competing one. Several people sensibly run a writing assistant and a reporting add-in side by side.

The question worth asking before any of it: is your problem the words, or the facts? Nearly every product in this category answers the first. Very few answer the second, and a roundup that lists them together without saying so is wasting your afternoon.

Frequently asked questions

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