Free Run-on Sentence Checker

Improve clarity in your writing with our free online run-on sentence corrector. Catch and correct errors for clear, polished text.

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What you need to know about run-on sentences

What is a run-on sentence?

A run-on sentence happens when two or more independent clauses (complete thoughts) are incorrectly joined together without the appropriate use of punctuation or conjunctions. Run-on sentences can make a passage difficult to understand and disrupt the flow of writing.

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Why use a run-on sentence checker?

Run-on sentences often result in unclear and unprofessional writing, causing confusion and wasted time. Our run-on sentence checker is a necessity for anyone who wants to improve their writing, ensuring clarity, accuracy, and efficiency.

Feel more confident in everything you write

Join over 3 million authors, students, and professionals improving their writing.

I am continually impressed with the positive input this program offers me every time I sit down to write. My skills have improved immensely since I bought it and heartily recommend it to anyone who wants to have more confidence in their own writing.

I’ve tried every free and paid writing/editing/grammar extension out there, and this by far is the best one my team and I have found. It’s fast, accurate, and really helps improve your writing beyond simple grammar suggestions.

ProWritingAid has been a resource in my writer toolkit for many years. The program helps me to craft and clarify my stories for a better reader experience. Your editor will thank you for making their job easier.

Supercharge your writing with ProWritingAid

Our editing tool doesn't just find run-on sentences; it corrects spelling, grammar, style, and more in real time.

Detect run-on sentences

ProWritingAid's run-on sentence checker highlights run-on sentences in your writing, such as missing commas, and offers suggestions to correct them.

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Example of confused words being corrected on our grammar checker

Avoid grammar and spelling mistakes

Whether you're crafting a short email or writing a novel, our tool ensures error-free writing. It catches and corrects grammar and spelling errors so you can be confident in everything you write.

Get style recommendations

ProWritingAid's comprehensive reports provide real-time style tips, such as avoiding overused words and varying sentence lengths.

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ProWritingAid works wherever you do

Write with clarity and precision across all the apps you use, whether they’re on desktop or online.

Run-on Sentence Checker FAQs

1. Does ProWritingAid autocorrect?

We'll provide you with suggestions, but the decision remains entirely yours. Maybe that missing comma was intentional! You can choose to accept or ignore each suggestion.

2. Can I fix run-on sentences in email? And on social media?

Absolutely! Our browser extensions (Chrome, Safari, Firefox, and Edge) will proofread your content on most websites, including Facebook, X, and Medium, as well as email providers, such as Gmail and Yahoo.

3. What else can ProWritingAid help with?

ProWritingAid has grammar, spelling, and punctuation checking built in so you can do everything in one place. The grammar report identifies misused commas, missing apostrophes, and more for a seamless writing experience.

4. Is ProWritingAid free?

Yes! With a free account, you can edit up to 500 words at a time. If you need to edit large documents, such as manuscripts or reports, you’ll need to upgrade to Premium.

5. Does ProWritingAid have a plagiarism checker?

Yes! ProWritingAid’s plagiarism checker will check your work against over a billion web-pages, published works, and academic papers, so you can be sure of its originality. Find out more about pricing for plagiarism checks here.