Early, widely used AI‑content detector popular among educators with free and affordable paid tiers.
GPTZero offers one of the lowest false‑positive rates on the market and outstanding robustness against paraphrase and homoglyph attacks, though its overall catch‑rate (~66 %) trails premium rivals.
66.5 %
0.01 %
Highly resilient against adversarial attacks
20
GPTZero measures text perplexity and burstiness—statistical hallmarks of human language—to estimate AI‑generated content probability.
Two complementary statistics flag writing that looks machine‑generated.
RAID benchmark shows ~0 % false‑positive rate at conservative threshold.
Accuracy barely drops (0.3 %) under homoglyph, paraphrase, or misspelling attacks.
| Benchmark | Accuracy | False Positive | Adversarial Robustness | Notes |
|---|---|---|---|---|
| RAID (6 M docs) | 80% | 0.01% | Accuracy drop ≈0.3 % | Top robustness across 11 attacks |
| Other Studies | 63.8% | 1.5% | Academic set; lower sensitivity vs Originality |
GPTZero excels at avoiding false accusations and shrugs off most adversarial tricks, but its moderate sensitivity means some AI slips through—pair with another detector for maximum coverage.
Freemium model: limited free checks daily, GPTZeroX from $9.99/month for classrooms, and pay‑as‑you‑go API for developers.
Teachers verifying essays and assignments.
Editors spot‑checking guest posts before publishing.
Academic integrity offices auditing submissions.
LMS or CMS developers embedding low‑FP detection.
Looking to explore other AI detection tools? Here are our curated picks with quick highlights so you can compare at a glance.
Premium detector with higher sensitivity.
For educators or anyone prioritizing zero false positives, GPTZero is hard to beat; pair it with a more aggressive detector if you need maximum catch‑rate.