Free AI Checker: 10 Best AI Detectors Compared for 2026
The best free AI checkers in 2026: GPTZero, ZeroGPT, Copyleaks, Scribbr and more. What AI checker teachers use and how accurate AI detectors really are.
Quick answer
The best free AI checkers are GPTZero, ZeroGPT, Copyleaks, Scribbr AI Detector and Sapling AI Detector. Many teachers use Turnitin through their school. No AI detector is perfectly accurate, so treat results as a signal, not proof.
AI checkers estimate whether text was written by a person or generated by AI. Teachers use them on essays, publishers on submissions, and writers on their own work before they hand it in.
The best free AI checker tools give a quick score and highlight suspicious sentences. But artificial intelligence detection is probabilistic: false positives happen, especially on short texts and writing by non-native English speakers. Here is how the main detectors compare.
Free AI checkers at a glance
| # | Tool | Best for | Free option |
|---|---|---|---|
| 1 | GPTZero | Education and essays | Free plan |
| 2 | ZeroGPT | Quick free checks | Free |
| 3 | Copyleaks | AI plus plagiarism detection | Free limited scans |
| 4 | Scribbr AI Detector | Students checking their own work | Free |
| 5 | Sapling AI Detector | Free sentence-level detection | Free |
| 6 | Turnitin | Schools and universities | Institutional license |
| 7 | Originality.ai | Publishers and SEO teams | Paid credits |
| 8 | Winston AI | AI text and image detection | Free trial |
| 9 | Pangram | High-accuracy text detection | Free limited checks |
| 10 | Undetectable AI | Checking against several detectors | Free checks |
Free options change often. Details reflect each product's public plans as of November 2026; always confirm on the official site.
How we picked these tools
Every tool here is listed in the allAilists directory, which we re-check every month for products that shut down, rebrand or change direction. We favor established products with a clear use case, add strong newcomers where they fill a gap, and note where the free option is limited. Nobody paid to be included and we do not use affiliate rankings.
The best free AI detectors
1. GPTZero: education and essays
GPTZero is one of the most widely used AI checkers in education, highlighting sentences likely written by AI and offering classroom features.
2. ZeroGPT: quick free checks
ZeroGPT gives a fast percentage score for pasted text, with no account needed for basic checks.
3. Copyleaks: AI plus plagiarism detection
Copyleaks checks for AI text and plagiarism, and can also detect AI-generated code.
4. Scribbr AI Detector: students checking their own work
Scribbr's free AI detector is aimed at students who want to check essays before submission.
5. Sapling AI Detector: free sentence-level detection
Sapling highlights which sentences look AI-generated and offers an API for developers.
6. Turnitin: schools and universities
Turnitin is the AI and plagiarism checker most teachers use, available through school licences rather than to individuals.
7. Originality.ai: publishers and SEO teams
Originality.ai combines AI detection, plagiarism and fact-checking for content teams and publishers.
8. Winston AI: AI text and image detection
Winston AI detects AI text and images and produces shareable reports.
9. Pangram: high-accuracy text detection
Pangram focuses on detection accuracy with low false-positive rates, according to its makers.
10. Undetectable AI: checking against several detectors
Undetectable AI runs text through multiple detectors at once. It also sells rewriting, which raises honesty questions in schools.
What AI checker do teachers use?
Most schools use Turnitin, which adds an AI writing indicator to plagiarism reports. Many teachers also use GPTZero or Copyleaks. Teachers rarely rely on a score alone: they compare a piece with a student's earlier work, look at version history and ask students to explain their writing. More classroom tools are in our AI tools for teachers guide.
How accurate are AI detectors?
No detector is 100% accurate. Results are less reliable on short texts, heavily edited AI text, and writing by non-native English speakers. Use detectors as one piece of evidence, never as the only proof. For AI-generated code, tools such as Copyleaks offer an AI code detector, but the same caution applies.
How to choose
- Use two detectors and compare results before drawing conclusions.
- Test with longer passages; short texts give unreliable scores.
- Keep drafts and version history to show your own writing process.
- For schools, follow your institution's academic integrity policy.