Good writing requires accurate grammar and spelling. Whether you're writing a professional email, a cover letter, a blog post, or a university essay, grammar errors undermine your credibility. An online grammar checker catches mistakes you might miss — even if you've read the same text multiple times.
Why Grammar Checkers Catch What You Miss
Proofreading your own writing is difficult because your brain auto-corrects errors as you read. You see what you intended to write, not what you actually wrote. This is especially true for:
- Homophones: "their" vs "there" vs "they're", "its" vs "it's", "effect" vs "affect"
- Subject-verb agreement: "The team are going" (British) vs "The team is going" (American)
- Missing commas: "Let's eat Grandma" vs "Let's eat, Grandma"
- Tense consistency: Switching between past and present tense within a paragraph
- Double words: "the the", "is is" — easy to miss on a quick re-read
- Apostrophe errors: "its" (possessive) vs "it's" (it is)
How to Check and Fix Grammar for Free
iConvertU's Grammar Fixer uses the LanguageTool API to check text against thousands of grammar and style rules.
Step by step
- Open iConvertU Grammar Fixer
- Paste or type your text into the input area
- Click Check Grammar
- Review suggested corrections
- Apply fixes and copy the corrected text
No account required.
What Gets Checked
A comprehensive grammar checker covers multiple levels of language correctness:
Spelling errors
Misspelled words and common typos. "recieve" → "receive", "definately" → "definitely", "occured" → "occurred".
Grammar errors
Subject-verb disagreement, incorrect tense, dangling modifiers, run-on sentences.
Punctuation
Missing commas after introductory clauses, incorrect apostrophe use, misplaced quotation marks.
Style suggestions
Wordiness, passive voice overuse, repeated words in close proximity, unnecessarily complex phrases.
Homophones and commonly confused words
"principle" vs "principal", "complement" vs "compliment", "stationary" vs "stationery".
Common Grammar Mistakes to Watch For
Its vs It's
Its is possessive: "The company lost its way." It's is a contraction of "it is": "It's a beautiful day."
Test: if you can substitute "it is" and the sentence still makes sense, use "it's". If not, use "its".
Fewer vs Less
Fewer is for countable nouns: "fewer mistakes", "fewer people". Less is for uncountable quantities: "less time", "less money".
Who vs Whom
Who is a subject (performing the action): "Who called?" Whom is an object (receiving the action): "To whom should I address this?"
Test: substitute "he" — if it works, use "who". Substitute "him" — if it works, use "whom".
That vs Which
That introduces a restrictive clause (essential to the meaning): "The report that was submitted late contained errors." Which introduces a non-restrictive clause (additional information, set off by commas): "The report, which was submitted on Friday, contained errors."
Grammar for Different Writing Contexts
Professional emails
Keep sentences short (under 20 words where possible). One idea per paragraph. Avoid overly formal language ("Please be advised that...") in favour of clear, direct phrasing.
Academic writing
Follow your institution's style guide (APA, MLA, Chicago, Harvard). Be consistent with tense — present tense for discussing research findings, past tense for describing what you did.
Blog posts and web content
Use active voice wherever possible. Short paragraphs (3–5 sentences). Use subheadings to break up long sections. Write for your reader's reading level.
Cover letters and CVs
Impeccable grammar is expected. A single typo in a CV can disqualify a candidate. Check every line multiple times, and use a grammar checker as a final pass.
Grammar Checkers vs Human Proofreading
Grammar checkers are excellent at catching mechanical errors — spelling, punctuation, subject-verb agreement. They're less reliable for:
- Contextual meaning (is this the right word for this sentence?)
- Nuanced style (does this read naturally for the target audience?)
- Domain-specific terminology
- Complex argumentation and structure
For important documents (job applications, academic papers, published articles), use a grammar checker first, then have a trusted human reader review as well.
Frequently Asked Questions
Does the grammar checker support languages other than English? iConvertU's Grammar Fixer uses LanguageTool, which supports 25+ languages including German, French, Spanish, Portuguese, Dutch, and more.
Will it catch all errors? No grammar checker catches 100% of errors. They miss contextual errors ("I went there yesterday" is grammatically correct but wrong if you went today), domain terminology, and intentional stylistic choices. Always review suggestions critically rather than accepting all changes automatically.
Is the tool suitable for academic essays? Yes, as a first-pass checker. Pair it with your institution's preferred style guide and a human proofreader for final submissions.
Is the tool free? Yes. iConvertU Grammar Fixer is completely free using the LanguageTool public API. No account required.
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