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Best Online Grammar checkers

Best Online Grammar checkers

Best Overall


It detected errors with much more accuracy than other programs we tested
This program provides weekly status updates
It’s easy to use in Word and various web apps
It struggles with overall content feedback
The program is not ideal for English learners or writing novices
A premium subscription isn’t cheap

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. Grammarly does a good job of finding these types of errors. This program integrates well with Microsoft Word and online text boxes.

In addition to using the program for everyday writing tasks, we put Grammarly through a series of tests to see how accurate it was. It detected errors in a document we devised containing many common English grammar errors with 30 percent more accuracy than the next best program in our tests. Copy editor Karie Anderson said she likes to use Grammarly as a final check on whatever document she is preparing.

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. However, Anderson really liked the free version. We talk more about that in the free vs. paid section below.

Best Value


Great at finding repetition in sentences
Has the best free version and an affordable lifetime subscription
Good at detecting sentence structure problems
Doesn’t correct online text boxes
Missed small punctuation errors that Grammarly fixed
Feedback isn’t as succinct as that of Grammarly

ProWritingAid is a great tool for student writers. It is structured differently than other programs we tested in that it emphasizes structural problems and is very adept at that. It did the best job of any program we tested when it came to highlighting and flagging problems in the student writing samples we used in our testing. It also looks for grammar and punctuation errors, which it did a decent job of detecting, but tended to miss more small punctuation errors than other programs.

ProWritingAid provides feedback to help you improve writing assignments, but its suggestions aren’t as succinct or helpful as the ones Grammarly provides. Still, you can go through and evaluate which suggestions to include in your final document.

Like many of the other programs in our side-by-side comparison there is a free version for this program. Like any program you will need to subscribe to the premium subscription to take advantage of important add-on features.  However, in contrast to a program like Grammarly, whose free version is vastly inferior to the premium option, the free version of ProWritingAid is a legitimate program that was the most helpful of any free program we tested. It also doesn’t inundate you with emails pressuring you to upgrade, which is nice.

And if you decide to upgrade, it’s not nearly as pricey as some of the other programs. A year’s subscription for ProWritingAid is about the same as a one-month Grammarly subscription. A lifetime subscription is only $175. This program, while it lacks certain functions like the ability to correct online text boxes, is a great value and an especially good option for college students.

Best Mobile App


Ginger supports more than 60 languages
It integrates with other apps and you can use its keyboard in those apps
The app performs sentence restructuring tasks
You have to pay a regular subscription fee to get its best features
Basic subscription leaves out key features
The app takes a little getting used to at first

Ginger’s mobile app, Ginger Keyboard, has a clean interface and functionality that can catch a lot of embarrassing mistakes before you send important text messages, emails or social media posts out to the world. You have a choice of different keyboards so you can pick one that suits your style. We liked the default keyboard, with its simple, clean look. It fixes spelling and grammar errors much more accurately than the autocorrect faux pas most of us have experienced. It also performs simple sentence restructuring tasks. It opens on your phone as a little notepad that you can compose text in or paste from another source for editing. You can then copy and paste it into a variety of apps. It easily integrates with other apps like Twitter, Facebook, LinkedIn and Gmail.

It supports more than 60 languages, with keyboards in a wide variety of alphabets. It has a translate tool, which functions at a slightly higher level than Google translate, but in a convenient, easy-to-access place on the app’s scroll-down menu. Unlike a regular text tool, it can add synonyms and missing words based on the context of your messages. It is easy to use and the suggestions and edits are simple and quick, which is nice for our fast-paced world. 

It also has predictive text capability that effectively predicts words you are about to type to speed up the typing process. While this is a common tool in most text programs, Ginger’s predictive text tool is better than average at predicting what you’re going to type. This useful app is available for both Android and iOS devices. You can download the Ginger app to your phone for free, but you will have to upgrade to a paid subscription to get its best features.

  • Read more in our review of Ginger

Best Translator

White Smoke

It has a feature-rich translator service
It is prone to suggesting inaccurate corrections

As a grammar checker, White Smoke 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 made incorrect suggestions because it failed to grasp the context of the sentence as a whole. Grammarly was much better at these kinds of tasks.

White Smoke, however, 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, White Smoke 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. Such a translator service can lighten the load of a professional translator. 

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

We researched the services’ claims about their software by installing the downloadable extensions on various browsers and websites 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 as a baseline and were not surprised to find that most grammar checkers do a better job than this popular word processor.

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.

We also felt it was important to get different perspectives by talking to people who have used the software as part of their regular professional and personal writing regimens. We spoke to copy editor Karie Anderson and writer Karina Fabian, who have both used Grammarly with positive results. In Anderson’s experience, Grammarly is generally better at catching errors than Microsoft Word. “While I don't use Grammarly as the sole tool for checking and verifying the grammar is correct, it serves as a good tool that catches some items that I've missed, especially if I am in a rush to quickly turn around a document,” Anderson said. Fabian said Grammarly was more adept than Google Docs at catching errors. “The best part for me is that it is more pervasive,” Fabian said. “It catches my errors on most of my online programs, including social media.”

We feel that online grammar checker software is 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.

Why Trust Us?

We spent two weeks researching, testing and reviewing the best online grammar checkers. We subjected each product to a battery of tests, including detection of specific errors in word processors, web browsers and email clients. We also performed a plagiarism detection test to compare how well each program found bootlegged content. We used the data from these tests to determine scores and benchmarks for accuracy, ease of use, correction speed and student paper evaluations.

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.

Copy editor Karie Anderson said that for students or people who work in the media, it’s worthwhile to invest in a Chicago or AP style guide. You can even take the next step and subscribe to a membership to one of those services and get regular updates so that your writing is both grammatically correct and stylistically up to date. “You really need to invest the time to learn the rules,” Anderson said.

Other Things to Consider

How does pricing work?
Online grammar check programs vary in price quite a bit. The services in our lineup range from the basic service SpellCheckPlus, which costs $14.95 for an annual subscription, to more multifaceted programs that can cost well into the hundreds of dollars. 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 most basic service, you pay $6.59 per month equaling $70.08 per year. For a Business subscription (WhiteSmoke’s most feature rich service) you pay $17.95 per month, or $215.40 per year. WhiteSmoke doesn’t offer any free options. If you sign up for a three-year subscription you pay less per month and you get substantial savings overall, but three years is a serious commitment.

In contrast, Grammarly offers a very basic free service and three payment options for its premium service. You can pay $29.95 for a month’s subscription, $59.95 for three months or $139.95 for an annual subscription. 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. And be warned, if you download a free version, you will be inundated with advertisements from Grammarly encouraging you to upgrade.

ProWritingAid has the most helpful free version among the applications we tested, but even it requires an upgrade to get the full benefits of the program. 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.

Other Types of Writing Help
Grammar is only one aspect of good writing. A grammar check program may give you all the tools you need, but there are other options available to help you produce your best writing. Some programs are designed for children, while others cater to more advanced writers. Here are some options to consider:

Spelling Software: While grammar applications have solutions for both grammar and spelling, there are programs out there that focus on teaching you the correct spelling of words. Most of these programs are designed for children, but some programs are geared toward adults who need a little help in that area, such as people learning English as a second language or those with challenges like dyslexia. Lessons are progressive and engaging and help you build skills as you go.

Writing Enhancement Software: These programs are more advanced than a grammar checker and focus on helping you improve your overall writing skills. The editing and reference tools are designed to help you refine your language skills, catch mistakes and produce polished prose. These programs include grammar checks as part of the package, and many of them offer stand-alone grammar options.

Robot Don: Another Grammar Program to Consider
Robot Don is another solid grammar checker. In addition to impressive grammar check tools, it specializes in detecting plagiarism and enhancing vocabulary. Lisa Griffin, a marketing specialist for Robot Don, said the program scans more than 60 trillion pages of internet pages and databases for plagiarized text, and it generally only takes about 5 seconds to show the results. “All the plagiarized text is highlighted in color and it’s easy to find the sources from which they were stolen,” Griffen said.

The vocabulary enhancement tool detects if you are using the wrong word or if there is a better word to express what you’re saying, and it gives you a list of synonyms to choose from on the dashboard. It also suggests replacement words if it sees you’re repeating the same word often.

Robot Don also checks for subtleties like sentiment and emotion. “It can detect anger, disgust, fear, joy and sadness,” Griffen said. The program looks for keywords and simply gives you a 1 if your essay expresses emotion or a zero if it fails to do so. If your text has a negative tone, it will let you know so you can make the necessary changes. While we haven’t fully tested and reviewed Robot Don yet, from what we can tell it looks to be a useful service.

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, I 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.

I used previously graded assignments to see if the software could pick up on problems with grammar and content. After accepting suggestions, I rated how much each program improved the documents and gave it a grade.

Editing & Feedback
I also wanted to see which programs detect issues the fastest and how smoothly they worked when I typed at my normal speed. 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 I 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, I thought a plagiarism checker was a valuable addition to the software. I used material from our site to evaluate how good the checker is at identifying copied material.

How Do I Edit My Own Writing?

Grammar checkers are a great way to catch embarrassing errors before you send out emails or turn in a college paper, but they don’t catch everything. Writers will tell you the best way to improve writing is to do a lot of it – write every day if you can. But you can become a skilled writer and still lack editing skills. If you are showing manuscripts to publishers or agents, it’s always good to have another set of eyes look at your manuscript before you submit it, though there are tricks you can do yourself to catch errors that might otherwise slip through.

Karina Fabian shared with us the five-step program she uses to minimize the number of errors in her own work. Here it is:

  1. Spell and grammar check.
  2. Change the font type and size and then reread it for errors. They will pop out.
  3. Print it and read it out loud. You will find tangled sentences, repeated words and phrases, and confusing parts because these things slow down your reading.
  4. Print it and read it backward, one sentence at a time. You will find an amazing number of errors because your mind is not moving with the flow of the narrative and filling in blanks for you.
  5. Run it back through spellcheck after fixing the errors to make sure you didn’t add some.

How Can I Improve My Grammar Mistakes?
A grammar check program can help you catch embarrassing errors, and when you pay attention to the reports you receive from a program like Grammarly, it can also help you catch them yourself. But that can only go so far in helping you improve your grammar skills generally. The writers and copy editors we spoke to had some ideas of ways you can improve your grammar skills.   

Karie Anderson, a copy editor we talked to, feels that for the average person trying to improve writing skills, one of the best things you can do is analyze what you read. “When I read for fun, I'll look at the punctuation in the book: How did the editor punctuate this sentence? Why did they put a comma here? Or I'll kind of test myself when reading a book.” She also suggests reading books specifically on style and grammar, like “Between You and Me: Confessions of a Comma Queen,” by Mary Norris.  

Anderson said the best way for the average person to improve grammar and sentence structure is to do a lot of reading and pay close attention as you read. She said exposure to all types of reading materials; whether it’s recreational reading like fiction or you’re reading something relevant to your industry, you can get a sense of style and grammar rules.

Karina Fabian, a fantasy and sci-fi novelist and marketing writer, said that for a person who already knows the rules of grammar, the most important thing is to pay close attention to what they have written. “Personally, I’ve found my own grammar skills have gone way downhill as I’ve gotten older, and that is in part due to the fact that I am doing so much quick, casual writing,” she said. “I have fallen out of good habits thanks to social media and software that automatically corrects common errors.” Slowing down and really reading what you’ve written will go a long way in helping to catch common errors, Fabian feels.

Advice for Writers
One writer we spoke to, Karina Fabian, has published more than a dozen books. Her advice for new writers is: “Write, submit, accept that rejections come, learn from them, write some more. Repeat.”

Fabian said if you self-publish, you should do yourself and your readers a favor and hire an editor. Grammar check programs are a good place to start when it comes to catching errors and fixing minor problems with the writing, like sentence structure, but they will only catch so much.

Fabian feels there is way too much badly written self-published content out there. Good or even great self-published work, like “The Martian” by Andy Weir, is well edited and had many sets of eyes look at it before publication. “You need outside eyes,” Fabian said. “Take the craft seriously if you want to publish. Otherwise, just write for fun on one of the fan-fic type sites or on a blog.”

Fabian said her books go through a crit group, which is a friendly peer critique group, and beta readers before going to a publisher, who then sends them to an editor and a copy editor. Having all these eyes looking at your work is very helpful, but Fabian has found that new errors are often introduced during this extensive editing process, so it’s important to re-read edits that come back to you. With social media and reliance on software that catches common errors for us, there is a tendency to get lazy and too casual. Fabian suggests the best way to catch your own errors is to slow down and really read what you have written.

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.

Contributing Reviewer: Noel Case