supadetect vs ZeroGPT
ZeroGPT is the most visited AI detector and is free to use without an account. So is supadetect. The difference is in what you are told: we publish measured error rates for each language, and we show the passages behind every Verdict.
| supadetect | ZeroGPT | |
|---|---|---|
| Who can use it | Anyone, with or without an account. | Open to anyone, no login needed. (ZeroGPT, checked 2026-11-10) |
| Free use | 5,000 words a month without an account (1,500 per Scan); 10,000 with a free account. | Up to 15,000 characters per check without an account. (ZeroGPT, checked 2026-11-10) |
| Paid price | Pro €18.99 a month or €119.88 a year, for 300,000 words a month. | Monthly and annual plans, 40% off when billed annually; prices are not shown on the plan page without signing in. (ZeroGPT, checked 2026-11-11) |
| Spanish | Separate thresholds for Spanish and English, measured on texts in each language; Spanish interface. | Interface in six languages including Spanish; the languages it detects are not listed. (ZeroGPT, checked 2026-11-11) |
| What it publishes about accuracy | Thresholds and error rates per language with confidence intervals, from a test set never used for tuning (below). | Calls itself "the most Advanced and Reliable" detector; its plan page gives no measured accuracy figures. (ZeroGPT, checked 2026-11-11) |
Facts about other products come from their own pages or from the reports linked, on the date shown. Prices and features change; check the source before deciding.
What to look for in a free detector
- Does it say how often it calls human writing AI, and in which language that was measured?
- Does it show which passages drove the result, so you can judge them yourself?
- Does it keep your text?
Our answers are on this page and on Accuracy. For other tools, check their own pages, linked in the table.
Our measured numbers
Rendered from the measurement file of Engine 2026.11-oculus-v0. We do not measure other vendors' detectors, so there are no competitor accuracy figures on this page.
| English human texts called Likely AI | 1.2 % (0.9–1.7) |
| English AI texts called Likely AI | 89.2 % (87.1–91.0) |
| Spanish human texts called Likely AI | 1.4 % (1.0–2.0) |
| Spanish AI texts called Likely AI | 99.5 % (98.8–99.8) |
What independent studies found about detectors in general
- Seven detectors flagged 61% of 91 human TOEFL essays written by non-native English speakers as AI-written (Liang et al., 2023). (Patterns / arXiv, checked 2026-11-11)
- A test of 14 detection tools found them "neither accurate nor reliable", and easy to fool with paraphrasing (Weber-Wulff et al., 2023). (International Journal for Educational Integrity, checked 2026-11-11)
- An audit by the University of Chicago's Becker Friedman Institute found large differences between commercial detectors, with only one meeting a 0.5% false-positive cap (Jabarian & Imas). (Becker Friedman Institute, checked 2026-11-10)