Free Grammar Checker for Common Mistakes (Rule-Based)
Catch repeated words, a/an mistakes, common misspellings and mix-ups like their/there with one-click fixes.
Rule-Based Grammar Checker
A rule-based checker. It catches common mistakes, not a full grammar engine.
Highlighted
- Word choice“Their” to “There”"Their" shows ownership. Before "is" you probably want "there".
- Repeated word“the the” to “the”The word "the" is repeated.
- Spacing“(space)” to “(one space)”More than one space in a row.
- a / an“a” to “an”Use "an" before "hour" (it starts with a vowel sound).
- Capitalization“i” to “I”The pronoun "I" is always capitalized.
- Spelling“recieve” to “receive”Possible misspelling of "receive".
- Word choice“its” to “it's”"Its" shows ownership. Before "a" you probably mean "it's" (it is or it has).
- a / an“a” to “an”Use "an" before "error" (it starts with a vowel sound).
- Word choice“Your” to “You're”"Your" shows ownership. Before "a" you probably mean "you're" (you are).
- Spelling“alot” to “a lot”Possible misspelling of "a lot".
- Word choice“then” to “than”After "better", comparisons use "than". "Then" is about time or sequence.
This is a rule-based checker. It catches common mistakes, not a full grammar engine. It looks for repeated words, extra spaces, a/an, sentence-start capitals, missing spaces after punctuation, a few their/there, your/you're, its/it's, then/than and affect/effect patterns, about 440 common misspellings, passive voice, and sentences over 40 words. It does not check commas, verb agreement, tense, or style, and it does not know your names or jargon. Always read suggestions in context before accepting them.
What this tool does and who it is for
This is a rule-based checker that catches common mistakes, not a full grammar engine. It flags repeated words, extra spaces, a/an mix-ups, missing capitals at the start of sentences, missing spaces after punctuation, a few their/there, your/you're, its/it's, then/than and affect/effect slips, and about 400 common misspellings.
Each flag explains the problem, and most come with a one-click fix. It also points out possible passive voice and sentences over 40 words as suggestions, with no automatic change.
Your text stays in the browser. Because it relies on patterns, it can miss mistakes and occasionally flag something that is correct, so read each suggestion in context.
Official Formula / Technical Standard
Real-World Worked Scenario
Enter or paste your text to perform instant transformations, count characters, and analyze typographic properties.
When people use it
A last pass on an email
Catch the doubled word, the stray double space and the your/you're slip before you hit send.
Proofing a cover letter or resume
Common misspellings and capitalization errors stand out quickly.
Cleaning pasted text
Fix all handles spacing and capitalization problems that come with text copied from PDFs or chat.
Spotting wordy sentences
The long-sentence and passive-voice hints help you decide where to tighten.
Notes for US users
- Spelling follows US conventions where it matters: for example, color and organize are treated as correct.
- Style guides differ on things like the serial comma, which this tool does not check. Follow the guide your school or employer uses (AP, Chicago, APA or MLA).
- For high-stakes documents such as a resume, a legal letter or a college application, have a person read it too.
Limits and what to double-check
- •It does not check commas, verb agreement, tense, sentence fragments, word choice in general or tone. Passing this tool does not mean the text is error-free.
- •It does not know your names, brands or technical terms, and a rare word that matches a built-in misspelling pattern may be flagged wrongly.
- •The affect/effect and its/it's checks use narrow patterns on purpose to avoid false alarms, so they catch only the obvious cases.
Expert Best Practices & Common Pitfalls
Recommended Best Practices
- •Review formatted text for readability and natural sentence flow.
- •Match casing and formatting conventions to your target platform or style guide.
- •Keep working drafts saved in your primary document editor.
Common Mistakes to Avoid
- •Relying entirely on automated tools without conducting human proofreading.
- •Using aggressive formatting or excessive capitalization in professional communications.
- •Pasting sensitive confidential drafts into untrusted web tools.
Features & Security Architecture
- 100% Client-Side: Zero server uploads ensure complete privacy and data confidentiality
- Fast Results: Processing happens on your own device, so there is no upload or server queue to wait for
- No Sign-Up Required: Completely free to use with no daily usage caps or account requirements
- Works on All Devices: Fully responsive across desktop, tablet, and mobile browsers
Frequently Asked Questions
How does the Grammar Checker (AI) work?▼
The Grammar Checker (AI) runs 100% inside your web browser using modern client-side JavaScript. It performs calculations, conversions, and document processing locally on your device without sending any data to external servers.
Is this grammar checker (ai) completely free to use?▼
Yes. This tool is completely free with no usage limits, no subscriptions, and no registration required.
Is my data private when using the Grammar Checker (AI)?▼
Yes. Because all operations execute locally on your computer or phone, your inputs, documents, and data never leave your browser.
Is this a real AI grammar checker?▼
No. It is a set of fixed rules and a word list that run in your browser. That makes it fast and private, but it does not understand your sentences the way a language model or a full grammar engine would.
What exactly does it check?▼
Repeated words, double spaces, a versus an, capital letters at the start of sentences and for the word I, missing spaces after commas and periods, selected their/there, your/you're, its/it's, then/than and affect/effect patterns, should of, common misspellings, passive voice and very long sentences.
Why was something correct flagged?▼
Pattern rules cannot see the full meaning. For example, a deliberate repeated word in a quotation or an unusual name can look like a mistake. Ignore any suggestion that is wrong for your text.
Does Fix all change everything?▼
It applies only suggestions that have an automatic fix, then re-checks. Passive voice and long-sentence hints are never changed automatically.
Is my text stored?▼
No. It is checked in your browser and nothing is sent to a server.