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The best AI grammar checkers and rewording tools

These AI content editing apps will make your writing shine.

By David Hartshorne · May 12, 2023
Hero image with the logos of the best AI grammar checkers and rewording tools

With all the hype around ChatGPT, it'd be easy to forget that AI tools have existed for a while. One area where AI has been working its magic for years is in AI grammar checkers.

We're not talking about AI writing generators here—these are purely AI editing and rewording tools designed to correct, refine, and improve your content. I use some of these apps daily as a prompt to make my writing more concise and, hopefully, more enjoyable.

So, if you're looking for an AI grammar checker or rewording tool to help you spot and fix typos, improve your grammar, or take your content to the next level, you've come to the right place. I considered dozens of apps and did in-depth testing on the top contenders to narrow it down to these six apps.

The best AI grammar checkers and rewording tools

  • Grammarly for all-around editing

  • Wordtune for rewriting, shortening, and expanding content

  • ProWritingAid for informative evaluation reports

  • Microsoft Editor for Microsoft 365 integration

  • WordRake for professionals wanting clarity

  • LanguageTool for multilingual writers

What makes the best AI grammar checker and rewording tool?

How we evaluate and test apps

Our best apps roundups are written by humans who've spent much of their careers using, testing, and writing about software. Unless explicitly stated, we spend dozens of hours researching and testing apps, using each app as it's intended to be used and evaluating it against the criteria we set for the category. We're never paid for placement in our articles from any app or for links to any site—we value the trust readers put in us to offer authentic evaluations of the categories and apps we review. For more details on our process, read the full rundown of how we select apps to feature on the Zapier blog.

There are plenty of lists of the best AI grammar checkers, so what makes this one different? For starters, many of those lists become intertwined with AI generative writing apps, but this one steers clear and focuses primarily on AI content editing apps. Second, I didn't just read these apps' marketing materials and customer reviews. I spent dozens of hours researching and testing the best AI rewording tools, paraphrasing apps, grammar checkers, and other similar tools.

For transparency, I've used some of these apps for many years in my writing career. But I was also keen to review the competition and see what I was potentially missing out on. For each one, I signed up and ran the editor through its paces, testing various scenarios, like spotting and fixing spelling and grammar errors or cutting fluff to make the text more concise. 

I was also mindful that some editing apps do one thing well, like paraphrasing, while others cover several bases. In my experience, I've not found one editing app that does everything well. And that's fine, as long as you know how to use a couple in tandem.

As I was testing the apps, here's what I was looking for:

  • Apps that focus on AI editing, not AI writing. As mentioned above, some tools focus on generative AI writing with a few editing features thrown in. Those tools didn't make the list. 

  • Spelling and grammar checker. This is probably the most common feature of AI content editing apps, but it's also the most unpredictable, with false negatives and positives. 

  • Options to create a custom lexicon/style guide. In some situations, especially when working in larger teams, you'll want to build a custom style guide, so everyone writes consistently.

  • The ability to rewrite, shorten, or lengthen content. Also known as paraphrasing or rewording, this is an invaluable feature when you want to write concisely or expand on a point.

  • Apps that check for plagiarism. A plagiarism checker scours the internet and highlights possible sources to ensure that no content has been taken from another source without permission.

Overall, I whittled the list down from 30 possibles to the best 6 AI grammar checkers and rewording tools.

Best all-around AI grammar checker


Grammarly, our pick for the best AI grammar checker overall

Grammarly works on multiple desktop and mobile platforms, browsers, and apps. It's a comprehensive AI editing tool covering all our features except paraphrasing. That said, it does prompt rewrites for conciseness and clarity automatically—it's just that you can't highlight a sentence or paragraph and ask it to rewrite/shorten/lengthen at will. But if you want to quickly reword sentences, you can use its free online paraphrasing tool.

As a long-time user of Grammarly, I'm familiar with its quirks. Sometimes the suggestions are off or totally wrong—but, hey, it's a machine, not a human, and it suggests more positives than negatives. One thing I like is the flexibility to switch the Chrome browser extension on or off. So, for example, I keep it switched off while writing in Google Docs, so I don't get interrupted with suggestions. I much prefer to copy the text into the desktop editor afterward and work in editing mode then. The browser extension also doesn't play well in WordPress, so I switch it off there again.

You'll have to upgrade to the business plan if you want to create a style guide for your organization. So, for example, monday.com could specify that employees use "monday.com" when writing about their company. 

Grammarly's AI grammar checker showing a style guide mistake with an explanation

The business plan also lets you configure snippets and brand tones, and provides an analytics dashboard so that you can identify team writing trends. 

The recent addition of a generative AI tool, GrammarlyGO, adds a few extra editing features, including options to identify gaps in writing, offer general improvement ideas, and pick out the main point. They aren't particularly insightful (yet), but it's nice to see Grammarly continuing to develop its tools.

Grammarly pricing: Free plan available, then $12/month for the Premium plan and $15/member/month (with at least 3 team members) for the Business plan. 

Best rewording tool for rewriting, shortening, or expanding content


Wordtune, our pick for the best rewording tool for rewriting, shortening, or expanding content

Wordtune is the perfect companion to Grammarly. While it doesn't check for plagiarism, it excels at rewriting, shortening, and expanding your content. It can even make suggestions for a more casual or formal tone. 

You can use it as an online editor—where you also get spelling and grammar suggestions—an add-in for Microsoft Word, or a Chrome extension. For example, working in Google Docs, it just hovers on-screen, waiting for you to put it to work. Simply highlight the text you want to rewrite, and it delivers several alternatives.

Wordtune's rewording tool offering various alternatives to a sentence

It's a great option for when you need a fresh take on what you've been working on.

Wordtune pricing: There's a free version limited to 10 rewrites per day, which is a good starting point. But the premium version—$24.99/month or $119.88/year— gives you unlimited access to all the features and the ability to rewrite entire paragraphs.

Best AI grammar checker for evaluation reports


ProWritingAid, our pick for the best AI grammar checker for evaluation reports

ProWritingAid works along the same lines as Grammarly, including the online editor where you can copy/paste your text or upload a document to work on. The interface is more crowded than Grammarly, with lots of reports and scores in the margins. It can be a little distracting initially, but it did highlight errors that Grammarly missed. For example, it stipulates that en dashes shouldn't have a space on either side.

Wortune's AI grammar checker telling the user that en dashes shouldn't have a space on either side

There are also desktop apps for Windows and Mac, browser extensions, and add-ons for Microsoft Word and Google Docs. I couldn't get the Chrome extension to work for Google Docs—I had to install the specific plug-in. And even then, you can only generate a Summary Report or an Improve Document Report like you get in the online editor, so it didn't save time by offering in-line suggestions.

One major plus for ProWritingAid is that you can create your custom style guide in the premium version—no need to upgrade further to a team version like you'd need to do with Grammarly. I tested this by adding a rule about not having spaces on either side of an em dash on the Zapier blog. For example:

  • INCORRECT: You can use it as an online editor — where you get spelling and grammar suggestions — an add-in for MS Word, or a Chrome extension.

  • CORRECT: You can use it as an online editor—where you get spelling and grammar suggestions—an add-in for MS Word, or a Chrome extension.

ProWritingAid also has a Rephraser tool (currently in beta), which works like Wordtune and offers several rewriting suggestions per sentence.

ProWritingAid pricing: There's a free version limited to 500 words and 10 rephrases per day, giving you basic writing suggestions. But you'll want the unlimited premium version with extra functionality to "edit like a pro." 

Best integrated AI grammar checker for Microsoft 365

Microsoft Editor

Microsoft Editor, our pick for the best integrated AI grammar checker for Microsoft 365

Microsoft Editor is only available on macOS and Windows desktop devices or as a free browser extension for Chrome and Edge. You can use a free Microsoft account to see basic spelling and grammar checks, but for premium features, you'll need to subscribe to Microsoft 365.

Here, you can define your writing style with grammar and refinements. For example, you can check for things like passive voice, adverb placement, and adjective order, or make your writing more formal or concise. 

You can use Microsoft Editor in Gmail, Outlook, LinkedIn, and other social media platforms on the web, but for serious editing, you'll want to use Microsoft Word. Here, you can activate the sidebar menu to see an overall score with corrections and refinements, plus an option to check for similarity (plagiarism). 

Microsoft Editor pricing: There's a free version with basic spelling and grammar checks. The premium version is available with a Microsoft 365 subscription, starting from $6.99/month.

Best AI grammar checker for brevity and simplicity


WordRake, our pick for the best AI grammar checker for brevity and simplicity

Wordrake edits for brevity and simplicity. You can choose:

  • Brevity mode to prioritize succinct writing

  • Simplicity mode to prioritize familiar word choices

  • Or both options to maximize your editing suggestions

The main caveat: it only works in Microsoft Word and Outlook. It uses the familiar Microsoft Word track-changes style to highlight possible improvements, which you then accept or reject.

WordRake targets professionals, like lawyers, who need to tighten legal briefs. (Imagine a world without legal jargon!) For example, it can:

  • Edit for plain language and reduce jargon and legalese

  • Cut throat-clearing introductory phrases

  • Remove unnecessary descriptive words and modifiers

  • Correct nominalizations and wordy adjective phrases

  • Remove redundancies and correct usage errors

  • Catch high-level grammar and punctuation mistakes

  • Edit conversational language to be more professional

  • Reduce wordiness and meet word counts

It does a very specific job, but a very important one. And it does it well.

WordRake pricing: There's a 7-day free trial; then it's $17/month ($129/year) for Microsoft Word (Mac or Windows) or $24/month ($199/year) for Microsoft Word and Outlook (Windows only).

Best AI grammar checker for multilingual writers


LanguageTool our pick for the best AI grammar checker for multilingual writers

LanguageTool is a multilingual grammar, style, and spell checker with an AI-powered sentence rephraser and custom style guide. The rephrased suggestions are as good as other apps like Wordtune, and the level of grammar and spelling matches Grammarly.

You can copy your text or upload a Word document into the online editor to check and fix errors or paraphrase it. Once you've made your changes, you can export it as a Word document or copy and paste your text back into your doc. Alternatively, you can install the software on multiple platforms, including: 

  • Desktop apps: macOS, Windows 

  • Browser extensions: Chrome, Edge, Firefox, Safari, Opera

  • Office plugins: Google Docs, Microsoft Word, OpenOffice, LibreOffice

  • Email add-ons: Gmail, Apple Mail, Thunderbird

Another nice feature in the settings is the option to select the Oxford comma in British English. (It's standard on other English varieties like U.S. and Canadian.) I also found the style guide worked as well as Grammarly and ProWritingAid when I performed similar tests.

Enter a text in a different language, and the app auto-detects the change and makes suggestions. For example, I pasted in some Spanish text, and it instantly switched to Spanish and highlighted some spelling and grammar errors.

LanguageTool pricing: Free plan available; then $24.99/month for individuals or $56.90/user/year for small teams of up to 20 members. 

Should you use an AI grammar checker or rewording tool?

As a freelance writer, I rely on AI content editing apps to highlight areas for improvement in my first drafts. Do I accept all the suggestions? No, I don't. And that's the rub. 

AI editing tools are an aid—they're not perfect. But between me and them, I can produce a solid first draft before my editors apply their superpowers. So my advice is to take them for a spin. Most have a free trial or free version to get you started, and then you can choose the premium AI grammar checker or rewording tool that works best for you.

Related reading:

  • How to self-edit your marketing writing

  • 6 ways to make your content stand out from AI writing

  • Create a digital assistant with Zapier and AI

  • ProWritingAid vs. Grammarly: Which should you use?

  • How to detect AI-generated content

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