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Best online grammar checkers 2021

Best online Grammar Checkers 2020
(Image credit: Future)

Wanting to improve your writing is a noble endeavor, and the best online grammar checkers can help you do just that. They can also save you from embarrassment, highlighting typos you’d missed in job applications and important letters, fixing your sentence structure and making sure your punctuation doesn’t leave you red-faced.

Anyone can benefit from using the best online grammar checker. Whether you’re a student turning in a paper at 3am or writing a memo to your CEO, a second pair of eyes to look over what you’ve written and scrutinise it for errors always helps. If that pair of eyes happen to be software-based, then all the better, because software never gets tired or has its own worries to contend with. 

Most of these applications come in the form of plugins for web browsers, or tiny files you download and which connect to an online service. They can work in offline applications such as Word, or online office suites such as Google Docs or free email services. While there are free versions, most lock their full potential behind a subscription. 

Upgrade to the paid-for version, and you may get extra features such as text translation, protection against plagiarism, and reports to see the mistakes you make regularly. And if you're applying for new work, we recommend combining a grammar checker with any of the best resume writing apps, to help you make a great first impression.

1. Grammarly: Best online grammar checker overall

(Image credit: Grammarly)


Easily the best online grammar checker we tested

Accurately detects errors
Provides regular updates
Easy to use across different apps
Premium sub is expensive

Grammarly provides the best online performance of any grammar checker we tested. It is faster and less buggy than other programs. It is also quite adept at catching errors and offering suggestions for fixing them. One of the most common errors among writers is misplacing or leaving out commas, and Grammarly does a good job of finding these types of errors. 

Once you finish writing a document, you can enable a session to get feedback from Grammarly. You can edit as you go, but it’s more efficient to wait until you’re finished composing. You can then scroll through the document to see the suggestions and fix errors. The service explains each suggestion to avoid confusion, but the suggestions will be most helpful to people well versed in grammar and punctuation terms. They aren’t learning tools and may be too advanced for novice writers or people just learning English. Another nice feature is the premium version provides weekly status updates to let you know how you’re doing. There is a free version available but it is quite basic and, once you sign up for it, Grammarly aggressively sends you email advertisements in an attempt to get you to upgrade.

It's our top pick because the accuracy it provides, and the extra tools on offer to help you fix persistent mistakes.

2. ProWritingAid: Best for students

(Image credit: ProWritingAid)


The top grammar checker for students and anyone who needs help with structure

Great at finding repetition
Affordable, and has a free version
Good at detecting sentence structure issues
Misses punctuation errors
Feedback isn’t all that great

If you're looking for a Grammar checker that will help with sentence structure, word repetition, and basic grammar, then ProWritingAid is a great pick. While it isn't as accurate as something like Grammarly when it comes to picking up pure grammar errors, it does a great job at suggesting changes to the structure of your work. So, if you're a student looking for advice on improving your assignment papers, or you're a budding freelancer trying to impress an editor, this might work for you.

ProWritingAid is relatively cheap too, so could be worth a shot if budget is an issue. On the downside, it does miss some grammar errors, and will occasionally make suggestions that worsen sentence structure. It also operates within its own software, so you can't use it to overlay Word or Google docs. That's fine, as its main use is for proofreading complete documents, rather than helping out as you type.

It has a plagiarism checker too, which works well for online content, but struggles with academic works. Handy for freelancers, but not-so-much for tutors checking student work. Overall, though, it's a decent pick.

3. Ginger Grammar: Best free version

(Image credit: Ginger)

Ginger Grammar

A great free option for checking emails and text as you type

Free version is good
It integrates with other apps
Has a decent translation tool too
Premium version needed for best features
It doesn't catch all errors, and does create inaccurate fixes

Ginger Grammar is a very versatile checker that comes with both free and premium options. While you do need to upgrade to the (reasonably priced) premium version to get all the features, the free version is a great tool for checking everyday writing. Simply instal it in your Chrome browser, for example, and it'll check most types of document you're working on. It overlays your word processing tool too, so it'll appear in Outlook (etc) and offer realtime suggestions. No need to paste text into a separate box or window.

There's a translator and plagiarism tool in the paid version too. The plagiarism tool works well, but the translator doesn't really offer anything beyond free tools like Google Translate.

Ginger’s predictive text tool is better than average at predicting what you’re going to type, and it manages to fix the majority of errors you throw at it. This useful app is available for both Android and iOS devices, and works in most modern browsers too. You can download the Ginger app for free, but you will have to upgrade to a paid subscription to get its best features.

4. WhiteSmoke Writing Enhancement: Good budget option

(Image credit: WhiteSmoke)

WhiteSmoke Writing Enhancement

A good budget grammar checker, with a decent translator built in

Great translation service
Has other grammar tools
Relatively cheap
Makes inaccurate suggestions

As a grammar checker, WhiteSmoke is not as sophisticated as some of the other programs we tested. It does a pretty good job of finding punctuation errors, like misplaced commas, but it occasionally makes incorrect suggestions because it fails to grasp the context of the sentence as a whole. It is much improved in 2020, though, and offers a decent suite of tools at a very tempting price.

WhiteSmoke does have a feature-rich translator service. It can provide word-to-word or full-text translations for 55 languages. While no automated translator is going to be perfect, WhiteSmoke claims it has a team of linguists who make regular improvements to the software, thus creating translations with the highest probability of being true to the source. However, before publishing an automated translation anywhere, we recommend having someone fluent in the language read it over and correct errors that will inevitably occur in any automated translator service.

How we tested online grammar checkers

We researched the services’ claims about their software by installing the downloadable extensions on various browsers and devices to see if their editing suggestions were helpful. We also looked at each software’s features to see how the free versions differed from the premium membership. Using student and professional papers, we checked each listed tool to see if it worked. We used the error detection in Microsoft Word and Google Docs as a baseline.

We signed up for each grammar checker service and composed sentences and documents with errors to test whether the software could find them all. In addition to looking for typical grammar and punctuation errors, we tested to see if the programs could pick up more subtle and complicated errors.

Our accuracy scores for these products may seem a little low. For example, the top-performing product only earned a 60 percent in our tests. These scores are based on the average number of errors the grammar checker found in documents we compiled that contained common grammatical errors. We included this information because we want our readers to know that this software, while helpful, can’t catch every kind of grammar or syntax error yet, but it does a decent job of catching errors overall.

How to choose the right grammar software for you

We feel that online grammar checkers are best for users who already have a working knowledge of grammar and punctuation. Occasionally, these programs give you bad advice, and we even found some errors on certain grammar check websites. So, if you’re new to English or want to improve your language skills, you may want to find a different, more comprehensive tool to help you proof your documents.

We found that accuracy is the most critical factor when choosing which grammar checker you should buy. The best programs effectively find errors such as improper use of adjectives, articles, punctuation and capitalization, as well as subject/verb agreement.

We also found correction speed to be a critical feature of online grammar checkers. You can expect these programs to detect errors in less than five seconds. Additionally, we found feedback generated by these applications helpful in teaching you what mistakes you’re making, thereby improving your writing skills.

We also talked to writers and copy editors, like Karie Anderson, Karina Fabian and Stephanie Presley, to hear about their experience using grammar check programs and to get insights into how to improve grammar and other writing skills.

Pick the right pricing
Online grammar check programs vary in price quite a bit. Several services on our site offer free membership options which give you very limited access to the programs. The services have various payment plans for annual subscriptions. For instance, if you sign up for WhiteSmoke’s Premium service, you pay $6.67 per month. For a Business subscription (WhiteSmoke’s most feature rich service) you pay $11.50 per month. 

By contrast, Grammarly offers a very basic free service, and two payment options for its premium service. You can pay $29.95 for a month’s subscription, or sign up for a whole year and get it at a cost of $11.66 per month. Obviously the longer you subscribe to Grammarly’s service the more cost effective it is. Once you sign up for a free membership, services like Grammarly will send regular advertisements urging you to upgrade for a premium membership. For services that offer free memberships, you are under no obligation to upgrade, but they will do their best, with varying degrees of aggressiveness, to get you to do so.

Free vs. Paid Grammar Check Programs
Many of the grammar check programs we reviewed offer free versions. The free programs are all quite basic and you will have to upgrade to get a grammar checker all the advanced features. For instance, Grammarly’s free version will catch basic grammar and spelling errors, but you’ll have to upgrade to get advanced punctuation, grammar, and context and sentence structure checks. That is not to say the free version isn’t helpful and worth having. A copy editor we talked to, Karie Anderson, was quite impressed with Grammarly’s free version.

“The spellcheck doesn't catch everything, but compared to MS Word, that still to this day can't distinguish affect/effect, Grammarly is pretty good,” Anderson said. “I like the customization it has as well. If there's a particular term that your organization uses a lot, you can simply add that word to Gammarly’s dictionary and it remembers it – and the dictionary function is far better than the Word one. For a free grammar-check tool, it's pretty sharp.” 

If you pay for a subscription you get added features like vocabulary enhancement suggestions, genre-specific writing style checks, plagiarism detection and numerous other features.

ProWritingAid and Ginger have the most helpful free versions among the applications we tested, but even they require an upgrade to get the full benefits of the programs. Free versions allow you to get a firsthand glimpse at the look and feel of the program and to see how it works. Testing free programs can help you decide which program works best for you before committing to one.

The best grammar checkers are sophisticated enough to accurately identify a variety of different problems in writing and offer appropriate suggestions for fixing any errors. In addition, we liked programs that let you customize their suggestions to match your genre and writing style – if you work in an industry that uses a lot of shorthand or job-specific vocab, its useful to be able to adapt the software to your needs.

(Image credit: ProWritingAid)

Editing & Feedback
Time is important when choosing editing software because if you have to wait around for the program to analyze your work, you might end up sending content with errors you didn’t see, especially in messaging applications. Many of these programs are intended for English language learners, so we also checked how accurate the translation features are in the software that have them.

Because electronic composition has made it easier than ever to accidentally plagiarize material, we thought a plagiarism checker was a valuable addition to the software. We used material from our site to evaluate how good the checker is at identifying copied material.

Ease of Use
We all want our writing to be professional and free from errors, but software can quickly get expensive. That’s why I looked at products that provide the most value, and I favored those that give you more tools for less money.

Compatibility is important to consider when you select an online grammar checking extension. You want to make sure the grammar checker works well with the browser and word processor you prefer. Programs that offer more features and work on more websites are a better value. Some even work on mobile devices, so you can produce error-free writing online from your phone, and I gave those products higher scores.

Help & Support
If you’re a writer working with a deadline, 24-hour support can be incredibly helpful. I looked for services that provide instant access to help. Grammar checkers that have live chat support or provide email and phone contact information fared better in our rankings.