Related
- HumanFlow vs Undetectable.ai — where we sit against the first of these, including where it beats us.
- HumanFlow vs QuillBot — and against the second.
- Every humanizer we track, ranked — on published limits rather than on claims.
Undetectable.ai vs QuillBot
HumanFlow is not one of the two tools on this page. We make a competing product, so weigh this accordingly — our methodology sets out how we source competitor figures and what we refuse to claim.
Compare the headlines and QuillBot wins outright. Compare what you can actually paste, and the answer depends on whether you write in paragraphs or in documents.
Last reviewed 16 August 2026 · The HumanFlow team
Why people compare these two
QuillBot is one of the most used writing tools on the web and Undetectable.ai one of the most heavily marketed humanizers, so a search for either surfaces the other within a page. They are also the two usual answers to the cheaper question people are really asking, which is whether the subscription they already hold is good enough.
Answering it means looking past both headline allowances, because they are stated in units that do not compare and neither describes what happens when you paste more than a paragraph.
Side by side
| Feature | Undetectable.ai | QuillBot |
|---|---|---|
| Entry price, monthly | $9.99 | Not published |
| Entry price, billed yearly | $5 | $8.33 |
| Included at entry | 10,000 words / month | Unlimited paraphrasing and unlimited AI Humanizer |
| Per-request cap | No stated per-request cap | No cap stated on Premium |
| Free tier | 250-word trial | 125 words per paraphrase; humanizer 125 words, 6 uses a day |
| Free per request | 250 words | 125 words |
Undetectable.ai figures read from their pricing page on 15 August 2026; QuillBot from theirs on 4 August 2026.
What actually separates them
Undetectable.ai sells 10,000 words a month and states no per-request cap. QuillBot Premium says unlimited humanizing and states no cap either. On those two sentences the comparison is over — except that one of those figures was counted and the other is a market position with a ceiling that exists and is not published.
The free tiers separate them much more sharply, and in the direction the paid tiers hide. QuillBot's free humanizer takes 125 words at a time, six times a day: 750 words daily, which is more than Undetectable.ai's entire 250-word trial. But it arrives in paragraphs, and a rewrite that cannot see the paragraph before it resets the register at every seam. Undetectable.ai's 250 words are contiguous and do not renew.
There is also a commitment difference that the monthly figures conceal. QuillBot publishes no month-to-month rate for Premium at all — the $8.33 is an annual plan divided by twelve. So the real choice is roughly $100 committed up front against Undetectable.ai's $60 for the same commitment, or $9.99 a month if you want to keep the option of leaving.
Which to pick
Pick Undetectable.ai if you want a humanizer specifically, you paste long documents, or you want to be able to stop after a month. A 10,000-word pool with no stated request cap takes a dissertation chapter in one pass.
Pick QuillBot if you want paraphrasing, grammar, citations and translation on one bill, you write in a language other than English, or you want a browser extension — and you are content to commit for a year, because there is no other way to buy it.
The claim we won't compare on
Neither tool's ability to get text past an AI detector appears above, and it is not an oversight. No vendor can observe or control the systems such a claim is about, detectors change without notice and disagree with each other on identical text, and every published bypass rate in this category was produced by the company selling the tool it tested. We publish none for our own product either — see why we publish no bypass rates.