The QuillBot + Grammarly Pipeline That Doesn't Work
We've talked to hundreds of users who tried this exact workflow: generate text with ChatGPT, run it through QuillBot to paraphrase it, then polish it with Grammarly. Sounds logical. Each tool handles a different step. The problem is that none of those steps address what AI detectors actually look for.
Here's what happens under the hood. ChatGPT produces text with extremely low perplexity — the word choices are highly predictable. QuillBot swaps those words with synonyms, which barely changes the perplexity score because the sentence structures remain uniform. Grammarly then tightens up the grammar, making the text even more polished and uniform — actually increasing the AI-like patterns. The final output might read differently, but statistically it still screams “machine generated.”
We benchmarked this pipeline. Starting AI text: 5% bypass rate. After QuillBot: 42%. After QuillBot + Grammarly: 51%. Three tools, multiple steps, still a coin flip. One pass through SupWriter: 99%+.
What Each Tool Actually Does (And What It Doesn't)
Being fair to both tools here — they're both good products that excel at their designed purpose. The issue is people using them for something they weren't built for.
- QuillBot is a paraphrasing tool. It excels at rephrasing existing text, finding alternative ways to express ideas, and avoiding direct plagiarism. It was built in 2017 for writers and students who need to reword source material. It is not an AI humanizer. Turnitin has literally trained their detector to spot QuillBot's patterns, complete with purple highlights flagging paraphrased text.
- Grammarly is a grammar and writing assistant. It catches spelling mistakes, fixes awkward phrasing, suggests tone adjustments, and improves clarity. It was built for better writing, not undetectable writing. Its own AI detector has a 34% false positive rate, which tells you a lot about its detection capabilities. We covered this in depth in our Grammarly alternative page.
- SupWriter is an AI humanizer. One purpose: make AI-generated text undetectable. It rewrites at the statistical pattern level — changing perplexity, burstiness, sentence length distribution, and other metrics that detectors measure. That's why it hits 99%+ while the others hover around 42-48%.
The Smarter Workflow: SupWriter First, Grammarly After
If you want the best of both worlds, here's what actually works: generate your draft with AI, run it through SupWriter for humanization, then give it a final pass with Grammarly for grammar polish. That workflow gives you undetectable text that also reads cleanly.
Many of our users already do this. SupWriter handles the hard part — making the text pass AI detection. Grammarly handles the easy part — catching stray commas and tightening phrasing. Two tools, two different jobs, both done well.
The cost comparison makes sense too. SupWriter at $9.99/month plus Grammarly's free tier gives you humanization and grammar checking for less than QuillBot Premium alone ($19.95/month). And you can verify everything with SupWriter's built-in AI detector before submitting.
Who Needs This Combination?
- Students — If your university uses Turnitin, neither QuillBot nor Grammarly will save you. SupWriter bypasses Turnitin 99%+ of the time.
- Content writers — Clients and editors increasingly run content through AI detectors. You need your AI-assisted drafts to pass cleanly. Check our guide to the best AI humanizer tools for a full comparison.
- SEO professionals — Google's algorithms can identify AI content patterns. Humanized content performs better in rankings because it reads naturally to both users and crawlers.
- Non-native English speakers — Both Grammarly's detector and Turnitin frequently flag non-native writing as AI-generated. SupWriter produces naturally varied text that avoids these false positives.
Related Resources
- Grammarly Alternative — Detailed Grammarly vs SupWriter comparison
- QuillBot Alternative — Full QuillBot vs SupWriter analysis
- Grammarly vs QuillBot 2026 — Head-to-head comparison
- Best AI Humanizer Tools (2026) — Complete ranked list
- Bypass Turnitin — 99%+ success rate guide
