GPTZero

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Best free AI detector – simply paste your text to instantly get an overall AI score and advanced sentence by sentence detection.

Yes. Independent benchmarks, like our partners at Penn State's AI Research Lab, and our own large-scale testing show that GPTZero is the most accurate AI detector, with a 99% accuracy rate when spotting AI-generated text vs. human writing. This means we correctly classify AI writing 99 out of 100 times and keep misclassification of text to an absolute minimum. Our results were further validated on RAID, a comprehensive, third-party benchmark where GPTZero was shown to be the most accurate AI detector in North America, detecting 95.7% of AI texts while only incorrectly predicting 1% of human texts as AI, an accuracy that jumps to over 99% when filtering to modern LLMs like GPT4. Unlike many competitors, GPTZero can reliably detect "mixed documents" (where human and AI writing are combined) with a 96.5% accuracy rate. While no AI detector can ever truly be 100% perfect, we are committed to being a leader in responsible adoption of AI generation and AI detection technologies.

GPTZero is consistently rated the most accurate and reliable AI detector across various use cases.

Reliability: In 2025, G2 ranked GPTZero the #1 most trusted and reliable AI tool, above Grammarly.
Accuracy: GPTZero is the most accurate AI detector with 99% accuracy rates across diverse datasets, independently reviewed by AI labs at top institutions. Independent reviewers, including Tom’s Guide, testing all popular detectors named GPTZero the most accurate.
Best Interpretability: GPTZero is the only detector that explains exactly why text is AI with natural language. GPTZero also has the most accurate sentence-level AI detection, with color-coded highlights on exactly where AI is used in an essay.