You have a document, and you want to find and fix all the problems with it before sending it over to your boss, your colleagues, your professor, or your client. What's the right tool to use? It really depends on what you're doing, and what result you want. There are countless AI products out there each with different strengths.

I compared seven popular ones with a real document review task, taking notes on how they performed across the full review workflow: how easily you can bring in a real document, what the AI can find, whether it can propose useful fixes, how you review those fixes, what happens to the original formatting, and how easy it was to use.

## Seven AI document review tools at a glance

These tools are built around different review workflows, but I've broken them down by what each one does best. My overall verdict is below, followed by a summary of my test for each tool.

- [Revise](#revise): fast and useful review yielding comments and tracked changes; intuitive to talk to in comment threads; citations not linked
- [Microsoft Word + Copilot](#copilot): also a good review without much of a wait, though without using comments or tracked changes; easy to use
- [Google Docs + Gemini](#gemini): took more nudging but successfully placed comments and made suggested changes; chat UI a bit hard to read
- [ChatGPT](#chatgpt): gave great feedback with good citations, but struggled with document editing; relied on Python; confined to upload/download
- [Claude](#claude): asked great questions before starting review, the best tool at context gathering; struggled with DOCX file format, also confined to upload/download
- [Grammarly](#grammarly): mostly focused on grammar and sentence polish, missing the bigger picture; comments disappeared after a page refresh; Pro upgrade gated
- [Spellbook](#spellbook): legal contract review against standards and playbooks

## What is AI document review?

A summary is not a review, nor is a simple rewrite. A useful document-review tool should take you through the entire workflow:

1. Find: identify errors, inconsistencies, weak reasoning, missing information, risky clauses, or style problems.
2. Explain: make the case for why an issue matters and point to the relevant passage or source.
3. Suggest: propose edits to content and formatting via comments and tracked changes.
4. Apply: let you selectively apply suggested fixes, accepting ones that make sense and rejecting ones that don't. Keeping you in control is important because the AI tool may not have all the context it needs.

Chatbots are often strong at finding and explaining, but they can't collaborate with you in a real document editor. AI writing assistants are fast at finding and fixing sentence-level problems, but many are limited to basic formatting and can't handle Word files properly.

An AI document editor is the best suited for agentic document review, and it has the hardest job: it must complete the loop while preserving a usable document.

## How I compared the tools

I evaluated each product against eight practical questions:

1. Document context: Can the AI reason about the whole document rather than one pasted paragraph?
2. Review depth: Does it catch only grammar, or can it assess structure, consistency, reasoning, and intent?
3. Actionable output: Does it return observations, comments, rewritten text, or edits to the actual document?
4. Human control: Can you inspect and accept or reject individual changes?
5. File fidelity: What happens to formatting, layout, comments, and revision history?
6. Speed: How long did it take to get useful improvements to my document?
7. Evidence: Does the AI cite its sources?
8. Friction to first useful review: Does the tool have a free tier? How hard is it to try?

To ensure a fair test, I used the same document with each tool: a [DOCX file](https://revise.io/docs/4hgvj07c-2odl7y5w/public) containing a simple legal contract with subtle hidden mistakes and flaws. Here is what I found.

## AI document review tools compared

### Revise: easy to use with great comment threads

[Revise](https://revise.io/ai-document-review) is a browser-based AI document editor. Import a DOCX, PDF, Markdown, or text file and the document opens in an actual word processor. The agent can read the full document, identify problems, leave comments, and propose edits directly in the page.

Revise took about 35 seconds to review the test document and left several insightful comments in the margins, pointing out things like contradictions and incorrect dates. Its first pass review was useful and cited local law.

![Revise editor showing review in margin comments](https://revise.io/blog/guides/ai-document-review/revise-review.png)

Revise caught several discrepancies that other tools didn't

The AI agent in Revise treats comments as a first-class feature - I was able to have conversations with it about specific sections of the document. And when I requested edits in a thread Revise already knew the context based on the comment's position in the document, and made appropriate surgical edits. Each suggestion it made could be accepted or rejected individually.

![Revise editor comment thread showing a question being answered](https://revise.io/blog/guides/ai-document-review/revise-citation.png)

Revise can answer questions and have a conversation in comment threads

![Revise editor comment thread showing an error being resolved](https://revise.io/blog/guides/ai-document-review/revise-reply.png)

Revise can edit the document contextually from a comment thread

When I exported my document back into .docx format, it retained all of its original formatting and included all of the still-unresolved comments and tracked changes Revise had made.

Overall Revise was a great general-purpose document reviewer, especially for a free tool. You can [try Revise](https://revise.io/ai-document-review) without creating an account, and it has a free tier with a daily AI limit, with no credit card required. Revise also offers [external AI connections over MCP](https://revise.io/help/mcp-server), which are free to use with no limits. Paid plans start at [$8 per month or $72 per year](https://revise.io/pricing).

### Microsoft Word with Copilot: reliable, the vanilla choice

[Microsoft 365 Copilot](https://www.microsoft.com/en-us/microsoft-365-copilot) is the natural choice when you're already using Word. When I asked Copilot to review the test contract, it found similar issues and discrepancies but the way it presented them was less intuitive. Rather than make inline comments, Copilot presented a stack of cards in its chat UI that I had to step through one at a time.

![Copilot showing issues in its chat response](https://revise.io/blog/guides/ai-document-review/copilot-review.png)

Copilot found issues with the test document but didn't use standard margin comments to identify them

When asked to address an issue, Copilot surprisingly didn't use tracked changes but rather a blue highlight and "undo" button. It wasn't what I expected, but it was still a decent performance.

![Copilot showing issues in its chat response](https://revise.io/blog/guides/ai-document-review/copilot-reply.png)

Copilot changes text directly, identified by a blue highlight

Obviously, Word had no trouble handling my .docx file and exporting it faithfully, preserving all my formatting. It was very easy to download offline copies or save to 365's cloud storage.

If you're already in Word and have [Microsoft 365 and Copilot access](https://support.microsoft.com/en-us/word/welcome-to-copilot-in-word), Copilot can do the job and is probably your easiest choice. The desktop Word workflow I tested is included with Microsoft 365 Personal, which offers a one-month trial and then costs [$9.99 per month or $99.99 per year](https://www.microsoft.com/en-us/microsoft-365-copilot/pricing/individuals). Copilot in Word is not available on any free tier.

### Google Docs with Gemini: decent but a bit confusing

[Gemini in Google Docs](https://workspace.google.com/products/docs/ai/) combines AI drafting and rewriting in the most popular collaborative word processor in the world. It's a natural choice for documents already in Drive. So how did it do?

When asked to review the test document, Gemini defaulted to simply offering a long markdown chat reply which was hard to read through even when expanding it into a full sidebar.

![Gemini presenting a document review in the Google Docs chat sidebar](https://revise.io/blog/guides/ai-document-review/gemini-review.png)

Gemini initially returned its review as a long chat response

Gemini eventually did leave contextual comments in the document, but not as itself - the comments were authored under my own name. This was confusing - if I'm working together with an AI agent, I want it to be clear what came from the agent versus from me. Even better if the agent and I can go back and forth within a comment thread, like in Revise.

![Google Docs showing an AI-generated comment attributed to the document author](https://revise.io/blog/guides/ai-document-review/gemini-smoking.png)

Gemini's comments appeared under my own name

Gemini was also able to apply edits using tracked changes, or as Google Docs calls it, suggestions.

![Google Docs showing an edit suggested by Gemini](https://revise.io/blog/guides/ai-document-review/gemini-reply.png)

Gemini applied document edits as Google Docs suggestions

It wasn't the smoothest experience, but Gemini did do the job and left intelligent comments. The biggest drawback was simply model choice - you can only use Gemini in Google Docs. If you like Gemini, and you're already in the Google ecosystem, then it's a fine choice.

For personal accounts, the full Gemini integration in Docs is available in [Google AI Plus at $9.99 per month](https://one.google.com/about/plans). The free version of Google Docs does not come with the Gemini AI integration, so just like Copilot this is not an option for free users.

### ChatGPT: great feedback, but weaker document handling

[ChatGPT](https://chatgpt.com/overview/) produced one of the most thorough reviews in the test. It took a lot longer than the other platforms I tried, but it left excellent comments. As it was working through my request, I noticed that ChatGPT seems to use Python scripts to work with .docx files in some kind of sandbox.

![ChatGPT reads .docx attachment using a Python script](https://revise.io/blog/guides/ai-document-review/chatgpt-python.png)

ChatGPT reads .docx attachment using a Python script

The feedback I got from ChatGPT was solid, and presented as a simple chat response (no surprise). It included excellent citations to local laws, but took a little more cognitive work to correlate each line in the bullet list to what part of the document it referred to. Notably, the section feedback was not in numerical order.

![ChatGPT presenting detailed feedback and citations from a document review](https://revise.io/blog/guides/ai-document-review/chatgpt-feedback.png)

ChatGPT returned detailed feedback with citations in a chat response

When I asked it to make changes to address its feedback, ChatGPT spent over 2 minutes generating a new .docx file using more scripts. The edits were made, but not with tracked changes so I could not easily see the before and after.

![ChatGPT providing an updated document without tracked changes](https://revise.io/blog/guides/ai-document-review/chatgpt-reply.png)

ChatGPT updated the test document in place without using tracked changes

ChatGPT is a general purpose chat app, not an AI document editor - so this experience wasn't surprising and all things considered it was pretty good. It's also worth noting that ChatGPT has plugins for both [Google Docs](https://chatgpt.com/plugins/plugin_connector_1p_ab21a553bfbc81919ea8fd1858e3ffa7) and [Revise](https://chatgpt.com/plugins/plugin_asdk_app_6a3eed981b50819180cbb53c6e8504ce), so it can work with external word processors.

ChatGPT's free tier includes limited file uploads and analysis; [ChatGPT Plus costs $20 per month](https://openai.com/chatgpt/pricing/) and raises those usage limits.

### Claude: by far the most thoughtful (and slowest)

[Claude](https://claude.com/product/overview) started its review doing something no other tool did: asking questions. Claude asked me two multiple-choice questions specific to my request before doing any work. This was very impressive.

![Claude asking a question about which perspective to review from](https://revise.io/blog/guides/ai-document-review/claude-intake.png)

Claude was the only tool that started off by asking questions

What followed was also the longest I had to wait for results. Claude Opus worked for over 11 minutes doing research and reading how to work with the test DOCX file. Like ChatGPT, Claude also seemed to work with Python to manipulate the document and spent more time on that than ChatGPT did.

![Claude working through a long document review](https://revise.io/blog/guides/ai-document-review/claude-long-response.png)

Claude spent more than 11 minutes researching and reviewing the document

At the end of it, Claude produced a valid .docx file with lots of thoughtful comments in it.

![Word document containing comments produced by Claude](https://revise.io/blog/guides/ai-document-review/claude-result.png)

Claude produced lots of thoughtful comments

![Word document showing tracked changes produced by Claude](https://revise.io/blog/guides/ai-document-review/claude-tracked-changes.png)

Claude was able to produce tracked changes in the test document

Given how thoughtful Claude was, I found myself thinking, "I wish Claude and I could go back and forth here." I wanted to discuss the comments with Claude, but doing so would require returning to the chat and having it generate another document. Copilot, Gemini, and Revise were the only tools I tested where I could continue the conversation inside the document editor.

It's worth noting that similar to ChatGPT, Claude has several integrations with external word processors: its [Google Workspace](https://support.claude.com/en/articles/10166901-use-google-workspace-connectors) connector lets Claude read documents in Google Docs; its [Microsoft Word plugin](https://marketplace.microsoft.com/en-us/product/office/wa200010453) puts Claude in a sidebar in Word 365 where it can read and edit; and Claude also has a [Revise connector](https://claude.ai/directory/revise) with reading and editing access.

Claude's free plan supports document uploads and file creation, subject to usage limits. [Claude Pro costs $20 per month or $200 per year](https://support.claude.com/en/articles/11049762-choose-a-claude-plan) and provides substantially more usage.

### Grammarly: not really built for documents

[Grammarly](https://www.grammarly.com/) is primarily a simple grammar checker, but it does have a document editor tool called Coda which they acquired in 2024. I gave it the same document review request.

At first Grammarly's AI chat just regurgitated a long chat response, but when asked to leave comments in the document it did do so pretty quickly. The whole review pass took about a minute.

The comments it made were relatively trivial, and it never tried to do any research or cite sources. This feature also seems to be gated on Grammarly's Pro subscription, which Grammarly heavily promoted to me in this "free sample."

![Grammarly's document editor showing an AI-generated comment](https://revise.io/blog/guides/ai-document-review/grammarly-comment.png)

Grammarly added comments after being prompted to review the document

Grammarly's document editor is not really a Word-capable editor. It does import and export .docx, but only preserves basic text and it doesn't render pages like a typical word processor would. It seems to be built more for bloggers, or people writing simpler things like emails.

The .docx it exported at the end had 0 page margins, which lowered my confidence in the tool not accidentally losing other formatting in my documents. I wouldn't try using this tool for any kind of complex reviews involving richly formatted documents.

![A word document with no page margins](https://revise.io/blog/guides/ai-document-review/grammarly-margins.png)

Grammarly exported the test document with zeroed page margins

Another thing that took me by surprise was when I refreshed the page, all the comments Grammarly had made disappeared. This might have been because it was just a free trial, but it made me feel like I had lost my work.

Grammarly has a free plan with 100 AI prompts, but the document agents and comments I tested appeared to require Pro access. [Grammarly Pro costs $30 per month, or $12 per month when billed annually](https://www.grammarly.com/pro).

### Spellbook: strongest for AI contract review

[Spellbook](https://spellbook.com/) is a product built specifically for reviewing contracts against legal standards, so I had high expectations. It did a very good job of reviewing the test document. Its AI agent first offered a simple table of suggested changes.

![Spellbook editor interface](https://revise.io/blog/guides/ai-document-review/spellbook-suggestions.png)

Spellbook first gave suggestions in a simple markdown table

When I asked for edits made to the document, Spellbook automatically opened its in-browser editor which looks a lot like Microsoft Word. It was able to make tracked changes to the document directly.

![Spellbook editor interface](https://revise.io/blog/guides/ai-document-review/spellbook-editor.png)

Spellbook opened the test document and modified it in place with tracked changes

The tracked changes used my own name, and I was not able to have a conversation by replying to them - but it was a very respectable result otherwise.

![Spellbook editor interface](https://revise.io/blog/guides/ai-document-review/spellbook-tracked-changes.png)

Spellbook's tracked changes survived DOCX export into Word

The plan I saw cost $500 per month, although Spellbook's public pricing is now customized by team size rather than presented as a universal list price. It offers a [free seven-day trial](https://spellbook.com/pricing), but is clearly targeting attorneys looking for a specialized product.

## My conclusions from this review

So, which AI document reviewer should you choose?

I think there is no right answer here, but some tools come out stronger than others. Revise was the fastest and easiest to use of all the tests I did, and it has a real free tier. With that said, it's a newer product and some users might feel more comfortable sticking to older, more proven editors like Word or Google Docs; Copilot and Gemini both did a respectable review pass.

If trying to do this with just an AI chat app like ChatGPT or Claude, I would definitely reach for one of their plugins rather than dealing with the minutes-long process of having them read uploaded documents and generate new copies of them. That workflow just felt slow and error-prone.

I would not recommend Grammarly for this - it's clearly targeted at fast, simple text polishing rather than serious document review.

And of course, if you're a law firm, there are multiple specialized products available to you like Spellbook and GC AI which will each bring with them more legal-oriented AI models and resources (albeit at a high price).

## Frequently asked questions

What is an AI document review tool?

An AI document review tool reads a complete document, identifies problems, explains why they matter, and suggests corrections. More capable tools can place comments or tracked changes directly into the document instead of returning a separate chat response.

Can ChatGPT review a document?

Yes. In my test, ChatGPT produced thorough feedback with useful citations from an uploaded DOCX file. It could generate a revised copy, but did not use tracked changes, making its edits harder to inspect.

Which AI document review tools support tracked changes?

Revise, Claude, and Spellbook produced tracked changes in this test, while Gemini made equivalent suggestions in Google Docs. Copilot used a blue highlight with an undo button, ChatGPT generated a new DOCX without tracked changes, and Grammarly left comments rather than proposed edits.

What is the best free AI document review tool?

ChatGPT and Claude offer limited document uploads on their free plans, while Revise can be tried without creating an account. Grammarly has a free plan but its document agents appeared to require Pro; Copilot and Gemini require paid plans, and Spellbook offers a seven-day trial.

What is the best AI tool for reviewing contracts?

Spellbook is purpose-built for legal contract review and produced useful suggestions and tracked changes in this test, although its pricing targets legal teams. Claude also produced a thoughtful contract review, but took considerably longer and required an upload-and-download workflow.

## Recommended reading

[![How to edit Microsoft Word files with ChatGPT\](https://revise.io/blog/guides/chatgpt-for-word/og.png) ## How to edit Microsoft Word files with ChatGPT June 28, 2026](https://revise.io/blog/chatgpt-for-microsoft-word-files-guide)

[![How to use Claude in Google Docs\](https://revise.io/blog/guides/claude-for-google-docs/og.png) ## How to use Claude in Google Docs June 23, 2026](https://revise.io/blog/how-to-use-claude-in-google-docs)