What is the best free online grammar checker? We tested six different grammar checkers and found the best one for you.

What Is The Best Free Online Grammar Checker?

We wanted to find the best free online grammar checker that works directly in the browser, with no sign-up and no download required. In other words, a grammar checker you can use instantly, without creating an account or paying for a premium plan. The tools we tested were ChatGPT, QuillBot, Reverso, Scribbr, LanguageTool, and GrammarCheck.

To do this, we ran the same text through each tool and compared how many errors they detected. Below is the exact text we used for the analysis.

Sample Text

The principle findings from the quarterly review remains clear and definately warrants further investigation. A large amount of seperate anomalies observed in the passed fiscal quarter are staggering; which will surely have an affect on our long term projections. This new dataset is meant to compliment the existing framework, and it’s primary purpose is to insure less errors occur. After reviewing the documents, a new conclusion was reached by the board. Everyday, the team must lie the new reports next to the old ones, hoping to see who’s predictions have been prooved correct. The board said, that they were more optimistic then before. The general consensus among the managers are that this represents a major breakthrough, and everyone felt it was a significant step forward. This will undoubtedly effect future policy.

In total, 20 grammatical, spelling, punctuation, and word-usage errors were intentionally planted in the text.

List of Errors

1. principle → should be principal
2. remains → should be remain (plural subject)
3. definately → should be definitely
4. large amount → should be large number (count noun)
5. seperate → should be separate
6. passed → should be past
7. Semicolon misuse → comma or period needed
8. affect → should be effect (noun)
9. long term → should be long-term
10. compliment → should be complement
11. it’s → should be its (possessive)
12. insure → should be ensure
13. less → should be fewer
14. Passive phrasing → “reached by the board” is weak and indirect
15. Everyday → should be Every day
16. lie → should be lay
17. who’s → should be whose
18. prooved → should be proved
19. Unnecessary comma → comma after “said” is incorrect
20. then → should be than

Results

1. ChatGPT

Result: 13 of 20 errors detected

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2. QuillBot

Result: 16 of 20 errors detected

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3. Reverso

Result: Unclear (sign-up required)

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4. LanguageTool

Result: 1 of 20 errors detected

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5. Scribbr

Result: 18 of 20 errors detected

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6. GrammarCheck

Result: 20 of 20 errors detected

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Ranking

Grammar Checker	Errors Detected	Performance
GrammarCheck	20 of 20	Best
Scribbr	18 of 20	Very Good
QuillBot	16 of 20	Good
ChatGPT	13 of 20	Average
LanguageTool	1 of 20	Needs Improvement
Reverso	Unclear	Sign-up required

If you’re looking for more grammar posts, try these:

1. 5 Common Grammar Errors & How To Fix Them
2. Punctuation For Beginners: What Is Punctuation?
3. Grammar For Beginners: All About Parts Of Speech
4. The Ultimate Grammar Cheat Sheet for Writers
5. Diction For Writers – Why You Need To Know
6. 16 Embarrassing Writing Mistakes to Avoid
7. 10 Easy Changes That Will Make You A Better Writer
8. 7 Free Online Grammar Resources You Can’t Ignore
9. Affect vs Effect & 34 Other Common Confusions
10. 44 Common Confusions To Annoy The Grammar Police

If you want to improve your grammar, have a look at The Complete Grammar Workbook.