Two Writing Tools, Very Different Strengths

Grammarly and QuillBot are the two most popular AI writing assistants, but they serve different primary purposes. Grammarly excels at catching errors and improving clarity. QuillBot excels at rephrasing and paraphrasing text. Both have expanded their feature sets over the years, creating significant overlap, but their core strengths remain distinct.

This comparison covers everything you need to decide which tool deserves your money, or whether you might want both.

Quick Comparison

Feature	Grammarly	QuillBot
Grammar Checking	Excellent	Good
Paraphrasing	Good	Excellent
Tone Detection	Yes	Limited
Plagiarism Checker	Yes (Premium)	Yes (Premium)
Browser Extension	Chrome, Firefox, Safari, Edge	Chrome, Firefox, Edge
Desktop App	Windows, Mac	No
Mobile Keyboard	iOS, Android	No
MS Office Integration	Word, Outlook	Word
Google Docs	Yes	Yes
Free Tier	Generous	Generous
Premium Price	$12/mo (annual)	$10/mo (annual)
AI Writing	Yes	Yes

Grammarly: Detailed Review

Grammarly has been the default writing assistant for millions of people since 2009. Its AI has improved dramatically, evolving from basic spell-check into a comprehensive writing coach that covers grammar, clarity, engagement, delivery, and now full AI text generation.

Grammar and Error Detection

This remains Grammarly’s strongest suit. It catches errors that other tools miss: subtle subject-verb disagreements, misplaced modifiers, incorrect comma usage, and commonly confused words. The suggestions include explanations of why something is wrong, which helps you learn over time rather than just accepting corrections blindly.

The Premium tier adds advanced suggestions for wordiness, passive voice overuse, unclear antecedents, and hedging language. These go beyond correctness into genuine writing quality improvement.

Tone and Style

Grammarly detects the tone of your writing and can flag when your text might come across differently than intended. Writing an email that sounds more aggressive than you meant? Grammarly will catch it. This feature works surprisingly well and is something QuillBot does not match.

The style guide feature on Business plans lets teams enforce consistent terminology, brand voice, and formatting rules across all members.

AI Writing Assistant

GrammarlyGO generates text based on prompts, rewrites selections, and can adjust the tone of existing content. It works directly within the editor, browser extension, and integrations. The quality is good for short-form content like emails, social posts, and brief responses. For longer content, it serves better as a starting point than a finished product.

Integrations and Availability

Grammarly works almost everywhere you write: browsers, desktop apps, mobile keyboards, Microsoft Office, Google Docs, Slack, and dozens of other platforms. This ubiquity is a major advantage. You set it up once and it follows you across your writing life.

Pricing

The free tier covers basic grammar, spelling, and punctuation. Premium costs $12 per month billed annually ($30 monthly) and adds advanced suggestions, tone detection, plagiarism checking, and full GrammarlyGO access. Business plans start at $15 per member per month with team analytics and style guides.

Try Grammarly free to test the grammar checking and basic features.

QuillBot: Detailed Review

QuillBot launched as a paraphrasing tool and has grown into a broader writing assistant. Its core strength remains rephrasing text in different ways while preserving meaning, a capability that no other tool matches in quality or flexibility.

Paraphrasing Engine

QuillBot’s paraphraser is genuinely best-in-class. Paste a paragraph and it offers multiple ways to rephrase it across different modes: Standard, Fluency, Formal, Simple, Creative, Expand, and Shorten. Each mode produces meaningfully different output, and you can adjust the degree of change with a slider.

This is invaluable for academic writers who need to incorporate source material without plagiarizing, non-native English speakers who want to express ideas more naturally, and content creators who need to rework existing text for different audiences.

Grammar Checker

QuillBot’s grammar checker is competent but does not reach Grammarly’s level. It catches common errors reliably: spelling mistakes, basic grammar issues, and punctuation problems. Where it falls behind is in advanced suggestions. Subtle issues like unclear pronoun references, complex comma rules, and stylistic improvements are less consistently caught.

Summarizer

The summarizer tool condenses long text into key points or a brief paragraph. It works well for academic papers, articles, and reports. You can choose between a bullet-point summary and a paragraph summary, and adjust the length of the output.

AI Writing and Co-Writer

QuillBot’s Co-Writer combines research, writing, and citation in one interface. You can search for sources, generate text, and create properly formatted citations without switching tools. For students and researchers, this integrated workflow saves significant time.

Integrations

QuillBot offers a Chrome extension, a Firefox extension, and a Microsoft Word add-in. It also works within Google Docs. The integration coverage is narrower than Grammarly’s. There is no dedicated desktop app, no mobile keyboard, and fewer third-party integrations.

Pricing

The free tier includes the paraphraser (with limitations on length and modes), basic grammar checking, and the summarizer with word limits. Premium costs $10 per month billed annually ($20 monthly) and unlocks all paraphrasing modes, unlimited word processing, the plagiarism checker, and full Co-Writer access.

Check QuillBot pricing for current plans and discounts.

Head-to-Head Comparison

Grammar Checking: Grammarly Wins

Grammarly is more thorough, catches more nuanced errors, and provides better explanations. If error-free writing is your primary goal, Grammarly is the clear choice. QuillBot’s grammar checker works for basic needs but misses issues that Grammarly catches consistently.

Paraphrasing: QuillBot Wins

QuillBot’s paraphrasing engine is significantly more capable than Grammarly’s rewriting features. The multiple modes, adjustable intensity, and consistent quality make it the better tool for anyone who regularly needs to rephrase text. Grammarly can rewrite sentences, but it does not offer the same level of control or variety.

Plagiarism Detection: Close, Grammarly Has a Slight Edge

Both tools offer plagiarism checkers on premium plans. Grammarly checks against a larger database and provides more detailed source matching. QuillBot’s checker is adequate for academic use but less comprehensive. Neither replaces Turnitin for serious academic submission, but both work well for pre-submission checking and content originality verification.

AI Text Generation: Grammarly Wins

GrammarlyGO produces higher-quality generated text across more contexts. The integration into Grammarly’s ecosystem means you can generate and then immediately polish in one workflow. QuillBot’s Co-Writer is useful, especially for research-oriented writing, but the generation quality is not as polished.

Value for Money: QuillBot Wins

At $10 per month versus $12 per month (annual pricing), QuillBot is cheaper. More importantly, QuillBot’s free tier offers more useful functionality than Grammarly’s free tier. Budget-conscious users get more from QuillBot without paying.

Ecosystem and Availability: Grammarly Wins

Grammarly works in more places. The mobile keyboard, desktop app, and broader integration library mean it covers more of your writing surface. If you want one tool that works everywhere you type, Grammarly delivers.

Who Should Choose Grammarly

Professional writers and editors who need comprehensive error detection and style improvement across all their writing platforms. The investment in Premium pays for itself quickly when your reputation depends on polished writing.

Business teams that need consistent brand voice and writing quality across multiple team members. The Business plan’s style guides and analytics provide oversight that QuillBot does not offer.

Non-native English speakers focused on correctness. Grammarly’s explanations help you understand why something is wrong, accelerating your English writing improvement over time.

Anyone who writes across many platforms. If you switch between email, documents, social media, and messaging throughout the day, Grammarly’s ubiquitous integrations mean you are always covered.

Who Should Choose QuillBot

Students and academics who need to paraphrase source material, summarize research, and generate citations. The paraphraser alone justifies the cost for heavy academic writing.

Content creators and marketers who regularly rework existing content for different channels or audiences. Turning a blog post into social media copy, adapting content for different markets, or refreshing older content is exactly what QuillBot does best.

Budget-conscious writers who want solid writing assistance without paying premium prices. QuillBot’s free tier is surprisingly capable, and the Premium plan costs less than Grammarly.

Writers who primarily need rephrasing rather than error correction. If your grammar is already strong but you want help finding better ways to express your ideas, QuillBot is the more relevant tool.

Can You Use Both?

Yes, and many serious writers do. The tools complement each other rather than conflicting. A practical workflow:

Draft your content
Use QuillBot to rephrase sections that feel clunky or repetitive
Use Grammarly for a final pass to catch errors and improve clarity

The combined cost of both Premium plans is about $22 per month on annual billing. If writing quality directly affects your income or academic success, this is a reasonable investment. If you need to pick one, choose based on your primary need: error correction (Grammarly) or rephrasing (QuillBot).

What About Free Alternatives?

Microsoft Editor is built into Microsoft 365 and offers grammar checking, style suggestions, and some rewriting capability. It is not as thorough as Grammarly but it is free with a Microsoft 365 subscription you might already have.

Google Docs built-in suggestions have improved and now offer grammar and style recommendations. Again, not as comprehensive as Grammarly, but useful for light editing.

LanguageTool is an open-source grammar checker that works well for multiple languages and is particularly strong for European languages beyond English.

None of these free alternatives match Grammarly or QuillBot at their core strengths, but they might be sufficient if your needs are basic.

The Verdict

Grammarly is the better all-around writing assistant. It catches more errors, works in more places, and provides a more comprehensive writing improvement experience. If you are choosing one tool, Grammarly is the safer bet for most writers.

QuillBot is the better specialized tool for paraphrasing and rephrasing. If that is your primary need, nothing else comes close. The lower price point and stronger free tier also make it the better choice for budget-conscious users.

Try both free tiers for a week with your actual writing. The difference will be obvious for your specific workflow, and you will know which investment makes sense.