The Big Comparison
Eleven tools, one notebook page. We tested detectors and humanizers — because "undetectable AI" is a claim worth checking.
Ratings are hand-drawn ink blots, not stars. ● = full blob, ◐ = half, ○ = empty. We mean it.
| Tool | Rating | Free tier | Best for | Our take |
|---|---|---|---|---|
| GPTZero | 10k words/mo | Teachers, quick checks | Most famous name. Decent free tier. Overconfident scores. | |
| Sapling | Generous API free tier | Developers, integrations | Underrated. Good API, sensible scoring. | |
| Winston AI | 2,000 words/mo | Content agencies | Clean UI. Tight free limit. Solid for batch checks. | |
| Copyleaks | Trial only | Universities, plagiarism + AI | Enterprise-grade. Expensive. Does both jobs. | |
| Originality.ai | Paid only | SEO agencies, publishers | Strict, paid, popular with content mills. | |
| ZeroGPT | Unlimited (ad-supported) | Casual checks | Free and everywhere. Accuracy is hit-or-miss. | |
| Crossplag | Limited free | Academia | Academic focus. Less known in the US. | |
| Content at Scale | Free checker | Bloggers | Ironic: also sells AI writing tools. | |
| Undetectable AI | Paid humanizer | People trying to cheat detectors | Humanizer, not detector. Beats some tools. Not all. | |
| HideMyAI | Limited free | Same as above | Rewrites AI text. Mixed results in our tests. | |
| HumanProduced (this site) | Free, unlimited | Quick sanity checks | Heuristic only. Use commercial tools for high-stakes decisions. |
How we test
Same three texts through every tool: a known ChatGPT essay, a human-written blog post, and a deliberately mixed paragraph. We note false positives and false negatives. Full methodology on How It Works.
Reviews updated when tools change — which is often.
Individual reviews
- GPTZero Review — the one everyone names
- Sapling AI Detector Review — the developer's pick
- Winston AI Review — polished, limited free tier
More reviews coming: Copyleaks, Originality.ai, ZeroGPT, humanizers, and guides for teachers and journalists.