We tested both tools across grammar correction, paraphrasing, AI writing assistance, plagiarism checking, and pricing to give you a clear recommendation.
| Feature | Grammarly | QuillBot |
|---|---|---|
| Grammar & Spelling Check | ✓ Best-in-class | ✓ Basic |
| Paraphrasing / Rewriting | ✓ (limited) | ✓ Industry-leading |
| AI Writing Generation | ✓ Grammarly AI (full) | ✓ Co-Writer (limited) |
| Plagiarism Checker | ✓ Premium (170B sources) | ✓ Premium only |
| Tone Detection | ✓ Yes | ✗ No |
| Clarity / Style Suggestions | ✓ Extensive | Limited |
| Browser Extension | ✓ Excellent | ✓ Available |
| Free Plan Generosity | Limited (basic checks only) | More generous (125-word paraphrase) |
| Summarizer Tool | ✗ No | ✓ Yes (free) |
| Paid Plan Price | $12/mo (annual) | $9.99/mo (or $4.17/mo annual) |
Grammarly's free plan includes grammar, spelling, and punctuation checking across every browser and app. Premium adds tone detection, clarity rewrites, and plagiarism detection.
Grammar checking is Grammarly's core competency, and it's the best in the market. In our tests across 30 documents with planted errors — comma splices, subject-verb disagreement, pronoun misuse, complex passive construction — Grammarly caught 96% of planted errors versus QuillBot's 71%. More importantly, Grammarly's suggestions are contextually appropriate: it rarely flags correct constructions as errors, which is a common failure mode in lesser grammar checkers.
Grammarly's Premium tier adds suggestions that go beyond strict grammar rules into style and clarity: eliminating wordiness, adjusting tone for the intended audience, rewriting sentences for concision and impact. These clarity suggestions are where Grammarly Premium justifies its price premium over the free plan. For professional writers, the difference between "grammatically correct" and "clear and polished" is where Grammarly earns its keep.
QuillBot's grammar checker is serviceable but notably weaker — it catches obvious errors but misses subtler issues and has a higher false-positive rate on non-standard but correct constructions. Grammar is simply not QuillBot's primary use case, and the quality reflects that.
Paraphrasing is QuillBot's signature feature, and it's the best single-purpose paraphrasing tool available. QuillBot's multiple paraphrase modes — Standard, Fluency, Formal, Academic, Simple, Creative, Expand, Shorten — let you control exactly how the rewrite changes the original text in terms of tone, length, and formality. In our testing, the Formal and Academic modes produced output that read like a competent human rewrite, not an obvious paraphrase.
Grammarly's rewriting features can produce paraphrase-like output, but they're designed to improve the original text's clarity and style rather than produce a structurally distinct rewrite. For students paraphrasing sources, researchers reformulating citations, or content writers needing to restructure licensed content, QuillBot's dedicated paraphrase engine is substantially better than Grammarly's rewrites.
The free plan includes paraphrasing up to 125 words at a time, which is useful for quick tasks. Premium removes the word limit and unlocks all paraphrase modes.
Grammarly has invested significantly in its AI writing generation features. Grammarly AI can draft emails, essays, blog posts, cover letters, and more from prompts — integrated directly into the Grammarly editor and browser extension. In our testing on common writing tasks (email drafts, essay introductions, meeting summaries), Grammarly's AI output was noticeably more polished and context-appropriate than QuillBot's Co-Writer feature.
QuillBot's Co-Writer provides a basic AI writing mode that works well for simple content, but it hasn't matched Grammarly's investment in the generation quality and UX of its AI writing product. For straightforward AI drafting alongside grammar checking in one tool, Grammarly is the stronger integrated choice.
Use Grammarly if: You write professionally (emails, reports, essays) and need polished output. You want tone detection to catch when your writing comes across as aggressive or unclear. You need a plagiarism checker with broad source coverage for academic integrity. You produce a lot of original content that needs editing, not rewriting.
Use QuillBot if: You frequently need to rephrase or paraphrase existing content. You're a student who needs to reformulate source material in academic writing. You want a summarizer tool (included free) to extract key points from long texts. You want strong paraphrasing on a tight budget — QuillBot's annual plan is significantly cheaper than Grammarly's.
Use both if: You're a student or researcher who needs academic writing polish (Grammarly) and source paraphrasing (QuillBot). Many serious writers and students subscribe to both — they cover genuinely different use cases and the combined cost ($4.17/mo QuillBot + $12/mo Grammarly on annual plans) is reasonable for the coverage both tools provide.
| Plan | Grammarly | QuillBot |
|---|---|---|
| Free Plan | Grammar, spelling, punctuation checks; limited AI rewrites | Paraphraser (125 words), summarizer, grammar checker (limited) |
| Paid — Monthly | $30/mo (Premium) | $9.99/mo (Premium) |
| Paid — Annual | $12/mo effective | $4.17/mo effective ($49.95/yr) |
| Business / Team | $15/user/mo (Business) | Not available (individual only) |
QuillBot is significantly cheaper at the annual plan price. Grammarly costs more but offers a broader feature set beyond paraphrasing.
Install the free Grammarly browser extension in 2 minutes and see the grammar and clarity improvements instantly on any webpage, email, or document.
Grammarly is the better all-around writing tool — superior grammar checking, tone detection, clarity rewrites, AI writing generation, and stronger plagiarism detection. At $12/month (annual), it's a solid investment for anyone who cares about professional writing quality. QuillBot is the better paraphraser — faster, more natural rewrites with more mode options, at a much cheaper price ($4.17/month annual). For students, researchers, and content writers who regularly rephrase sources or reformulate text, QuillBot's specific strength is worth the small separate subscription. For most users, Grammarly is the higher-value starting point; QuillBot is worth adding specifically if paraphrasing is a major part of your workflow.
Grammarly is better for grammar checking, tone detection, and overall writing polish. QuillBot is better for paraphrasing and rewriting existing text. They serve different primary use cases — the question of which is "better" depends entirely on what you need most.
Yes — many students and writers use both. A typical workflow: use QuillBot to paraphrase a source passage, then paste it into Grammarly to check grammar and clarity. They complement each other without major overlap.
Students benefit from both. Grammarly catches grammar errors and improves writing quality in their own original work. QuillBot's paraphraser helps reformulate source material for citations, and both offer plagiarism checkers on their paid plans. Many students subscribe to both on annual plans for roughly $16/month combined.
Grammarly's free plan includes grammar, spelling, and punctuation checking. Advanced features — tone detection, clarity rewrites, full-sentence suggestions, and plagiarism checking — require Grammarly Premium ($12/month annually, $30/month monthly).
QuillBot Premium includes a plagiarism checker but does not currently offer a dedicated AI content detector. For AI detection, tools like Originality.ai or GPTZero are more specialized options.
QuillBot's free plan includes paraphrasing up to 125 words at a time, a summarizer, and basic grammar checking. The Premium plan ($9.99/month or $4.17/month annually) removes the word limit, unlocks all paraphrase modes, and adds plagiarism detection.
Grammarly's Premium and AI features include sentence rewrites that can produce paraphrase-like output, but it's not a dedicated paraphrase engine — it's focused on improving clarity and style in your existing writing. For dedicated paraphrasing, QuillBot's specialized paraphrase modes are significantly stronger.
Grammarly is generally the better choice for non-native speakers — it catches grammar errors, explains suggestions, adjusts for formal vs. casual register, and can help develop a more natural-sounding writing style over time. QuillBot's Fluency mode is also useful for smoothing out non-native phrasings, but Grammarly's broader set of improvements makes it the primary tool for language learners.
Both Grammarly and QuillBot are editing tools — they work with content you've already written. If you need to generate content from scratch, consider pairing either with a dedicated AI writing tool. Jasper is the strongest option for professional content teams — it generates long-form blog posts, marketing copy, and brand content with a level of quality that complements Grammarly's editing strengths well. Use Jasper to draft, Grammarly to polish.
For a more budget-conscious alternative that handles both AI writing and basic grammar checking in one tool, Writesonic is worth evaluating — it includes its own grammar and SEO checks alongside AI generation, which can reduce the number of separate subscriptions needed. It won't replace Grammarly's depth of grammar intelligence, but for casual writers who don't need professional-grade correction, Writesonic's all-in-one approach is a reasonable compromise.
Students specifically should also consider Notion AI, which integrates AI writing assistance and summarization directly into a note-taking workspace — useful if you're already organizing your research and study notes in Notion rather than needing a separate writing assistant subscription.
