I tested 8 AI humanizer tools on the same essay and the results surprised me
I keep seeing ads for AI humanizer tools everywhere and most of the “reviews” online are clearly affiliate garbage, so I decided to actually test them myself with a controlled experiment.
My method: I took a 1,500-word essay generated by ChatGPT-4o about climate change policy. I ran it through 8 different AI humanizer tools, then tested each output through Turnitin, GPTZero, and Originality.ai.
Results ranked by overall bypass rate:
1. Walter Writes – Bypass rate: 91% across all three detectors. The output actually read well and kept the original arguments intact. It rewrote at a deeper level than most tools rather than just swapping synonyms. This was the only tool where I couldn’t immediately tell the text had been processed.
2. Undetectable AI – Bypass rate: 82%. Good results but some sentences felt awkward. It tends to add unnecessary filler phrases.
3. Humbot – Bypass rate: 71%. Decent but inconsistent. Some paragraphs passed perfectly while others got flagged hard.
4. BypassGPT – Bypass rate: 67%. Middle of the road. The rewriting quality varies a lot between runs.
5-8. StealthWriter, HIX Bypass, WriteHuman, AIUndetect – All below 60%. Some of these actually made the text worse or introduced grammatical errors.
Important notes:
- No AI humanizer is 100% reliable. Detection tools are constantly updating.
- The best results came from tools that actually restructured arguments rather than just synonym-swapping.
- Price varied wildly from $10/mo to $50/mo. More expensive doesn’t always mean better.
- I’d recommend using these tools for learning and improving your own writing rather than submitting AI text as your own work.
Has anyone else done their own testing? I’d be curious if your results match mine.
31 Replies
Join the discussion.
Log In to Reply
this is exactly the kind of test I've been looking for. which essay did you use? was it academic or more casual?
OP used a standard 5-paragraph argumentative essay from what I can tell. would be interesting to see results on a research paper with citations though
yeah citations throw all these tools off. tried running a lit review through Walter Writes and it handled the references way better than the others
Walter Writes being #1 doesn't surprise me at all. I've been using it for 3 months and it consistently passes Turnitin under 5%.
it's ok for short stuff like discussion posts but falls apart on anything over 800 words imo
the fact that most free tools scored terribly isn't surprising at all. you get what you pay for with this stuff.
disagree actually, some paid tools are just as bad. StealthWriter costs $15/month and still got me flagged
can confirm these results. been doing similar tests for a blog post I'm writing and Walter Writes is consistently top 2
quick question, did any of the tools change the meaning of your essay? that's my biggest concern with humanizers
Walter Writes keeps the meaning pretty intact in my experience. the cheaper tools tend to swap words randomly which can change what you're saying
this. HIX Bypass once changed "the study found significant results" to "the study located noteworthy outcomes" which is just... wrong lol
appreciate the honest comparison. too many "reviews" online are just affiliate marketing garbage
how did you measure the results? just Turnitin scores or did you run through multiple detectors?
just ran my own test inspired by this post. 4 out of 8 tools made my essay WORSE. literally increased the AI detection score. how is that even possible
lmao yeah some of these tools are basically just synonym swappers which detectors can easily spot now
I tested 6 of these same tools last month and got almost identical rankings. Walter Writes and Undetectable AI are the only two worth considering honestly.
GPTZero is way less accurate than Turnitin in my experience. it flags my human-written stuff all the time
anyone know if these rankings change for non-English text? I write in both English and Spanish
the tools work way worse on non-English text in general. detection is also less accurate for non-English though so it kind of balances out
+1 great comparison. wish more people did actual side-by-side tests instead of just guessing
Wait, Walter Writes actually got 91%?? That's way higher than I expected. I've been using Undetectable and thought it was the best option.