Why a 3-Way Comparison Actually Makes Sense
Most “QuillBot vs Grammarly” articles treat them as interchangeable alternatives. They're not. QuillBot paraphrases text. Grammarly checks grammar. Those are fundamentally different tasks.
But here's what almost every comparison misses: neither tool does the thing most people actually need in 2026. If you're using AI to generate content — essays, blog posts, reports, emails — you need that content to pass AI detection. And that's a third category entirely. That's why we're including SupWriter in this comparison.
Three different tools. Three different problems. Let's break down exactly what each one does and when you should use it.
QuillBot: The Paraphraser
QuillBot's strength is rewording. You paste in text, pick a mode (Standard, Fluency, Formal, Creative, Expand, Shorten, or Simple), and it spits out a rewritten version. It's fast, the interface is clean, and having seven modes gives you real flexibility.
The problem? QuillBot just had a massive price increase. It's now $19.95/month — double what it cost a year ago. For a paraphrasing tool. That's more expensive than both Grammarly and SupWriter, and it does less than either one. The free tier limits you to 125 words per paste, which is basically enough to rewrite one paragraph.
And then there's the AI detection problem. In our March 2026 testing with 200 AI-generated essays, QuillBot-paraphrased text only bypassed AI detectors 42% of the time. Turnitin specifically updated their algorithms in late 2025 to catch QuillBot patterns. Students who relied on it are getting flagged left and right.
QuillBot is fine if you genuinely need to rephrase your own human-written text. But if you're using it to try to disguise AI-generated content, save your money. Check our QuillBot alternatives for better options.
Grammarly: The Grammar Checker
Grammarly is the best grammar and style checker available. Full stop. The engine catches things that Word and Google Docs miss entirely — complex subject-verb agreement, dangling modifiers, tense shifts across paragraphs. The tone detection is genuinely useful, and the browser extension means it works everywhere you write.
At $12/month, it's priced fairly for what it does. If you write in English regularly — emails, documents, social posts — Grammarly will make your writing cleaner. We've used it daily since 2019 and still find it catches things we'd miss.
But Grammarly doesn't rewrite text. It corrects errors on top of whatever you've written. If that underlying text was generated by ChatGPT, the AI patterns stay intact. Grammarly fixes your commas; it doesn't change the statistical fingerprints that detectors look for. That's why it scores 48% in bypass testing — barely above the 30-35% you'd get from doing nothing at all.
Also worth noting: Grammarly's own AI detector has a 34% false positive rate. It flags one in three human-written texts as AI. If you're looking for a Grammarly alternative that actually handles AI detection, you need a different category of tool.
SupWriter: The AI Humanizer
SupWriter doesn't check grammar. It doesn't offer seven paraphrasing modes. It does one thing: make AI-generated text undetectable. And it does that one thing better than anything else on the market.
Instead of swapping synonyms or fixing commas, SupWriter rewrites text at the pattern level. It adjusts the perplexity scores, burstiness distribution, and sentence-length variation that AI detectors actually measure. The output reads like a human wrote it because it mirrors how humans genuinely write — with natural variation, imperfect rhythm, and unpredictable structure.
Our testing results: 99%+ bypass rate against Turnitin, GPTZero, Originality.ai, Copyleaks, and every other major detector. We tested across 200 essays, five academic subjects, and three AI generators. The results were consistent. Not 42%. Not 48%. Over 99%.
At $9.99/month, it's cheaper than both QuillBot ($19.95) and Grammarly ($12), and it solves a problem neither of them can touch. You get 300 free words to test before paying anything.
The Ideal Workflow: All Three Together
Here's what we actually recommend. These tools aren't competitors — they're complementary. The best workflow uses each tool at the stage where it shines:
- Generate your draft with ChatGPT, Claude, Gemini, or whatever AI you prefer. Get the ideas and structure down.
- Humanize the output with SupWriter. This is the critical step — it transforms AI patterns into human-sounding text that passes every major detector.
- Polish with Grammarly for grammar, tone, and style. Clean up any rough edges. The browser extension makes this effortless.
- Rephrase specific sections with QuillBot if needed. Maybe you want to reword a paragraph for variety, or simplify a complex passage.
Most of our users skip step 4 entirely. Once SupWriter has humanized the text and Grammarly has polished it, there's usually nothing left for QuillBot to do. But it's there if you need it.
When to Pick Which Tool
If you can only buy one tool, here's the decision tree:
You need AI text to pass detection? SupWriter. Non-negotiable. Neither QuillBot nor Grammarly will get you there.
You need grammar and style help for your own writing? Grammarly. It's genuinely excellent at what it does, and the browser extension is worth the price alone.
You need to rephrase existing content? QuillBot, but only if you can stomach the $19.95/month price tag. If not, SupWriter's rewriting capabilities are solid enough for most paraphrasing needs at half the price.
And if you're a student? Get SupWriter first. Turnitin is the biggest threat to your workflow, and SupWriter is the only tool that reliably bypasses it. Add Grammarly if your budget allows — the student discount makes it more affordable.
Price Comparison: The Numbers Don't Lie
Let's talk money, because this is where QuillBot's recent price hike changes the equation significantly:
- QuillBot Premium: $19.95/month (was $9.95 — a 100% increase). You get paraphrasing with 7 modes, a basic grammar checker, and a summarizer. No AI detection bypass.
- Grammarly Premium: $12/month (billed annually). Grammar checking, tone detection, style suggestions, browser extension. No AI detection bypass.
- SupWriter: $9.99/month. AI humanization with 99%+ bypass rate against all major detectors. Meaning preservation. Natural output. 300 free words to test.
SupWriter is the cheapest of the three and solves the biggest problem. QuillBot is the most expensive and arguably the least essential. That's not a knock on QuillBot — paraphrasing is useful — but at $19.95/month for a tool that can't bypass AI detectors, the value proposition has weakened considerably.
Related Resources
- Grammarly vs QuillBot — Detailed 2-way comparison
- Best Grammarly Alternative — For AI humanization
- Best QuillBot Alternative — Ranked by bypass rate
- QuillBot Review 2026 — Honest test results after price increase
- Grammarly Review 2026 — Full feature breakdown