Looking for a free AI detector people have actually tried

QuillBot gives more context than a bare human-or-AI label. Its report separates likely AI-generated writing from AI-refined or human-written material, then marks suspicious sections for review. It supports 20-plus languages, making it a stronger choice for multilingual submissions.

The free detector uses the same detection system offered to Premium users. Free accounts can upload one file at a time, while Premium raises that to 20 files. A published Scribbr comparison scored QuillBot's free detector at 78% on its test set, though no benchmark can predict every real draft.

QuillBot is useful as a second opinion when Clever produces an unexpected result. The smaller per-check allowance makes long reports less convenient, yet the result categories are unusually readable.

Best forEditors or students checking drafts written in several languages

GPTZero feels built around document review rather than a quick novelty score. The free plan includes up to 10,000 scanned words per month, multilingual detection, plus writing feedback. Its highlighting helps reviewers find passages worth discussing instead of treating the final number as a verdict.

The service has also attracted plenty of real-world testing. In the supplied Reddit thread, GPTZero marked the original sample as 99% AI-generated, then fell to 55% after the text was rewritten. That sharp movement shows why edited material needs human review.

Monthly credits are the catch. Occasional users should have enough, though a teacher checking several classes can burn through the allowance quickly. It remains one of the more useful choices when the report must support a conversation about a draft.

Best forTeachers who want highlighting, writing feedback, plus document-oriented reports

Scribbr is straightforward. Paste a draft, run the check, then review the percentage plus passage labels. It allows unlimited free checks with up to 1,200 words per submission, no registration required.

The detector supports English, Spanish, German, plus French. Scribbr's own published comparison puts its free detector among the better no-cost choices, but its product page also says no detector reaches complete accuracy. That warning matters most for formulaic academic prose, which can resemble model output.

The 1,200-word ceiling works for an essay section, application letter, or article draft. Longer papers need to be divided, which can produce different scores when context disappears between sections.

Best forStudents seeking a no-account check with simple passage classifications

Sapling offers a more technical result than most free checkers. Its web detector returns an overall probability, local highlights, plus optional sentence perplexity scores. The company recommends using at least 50 words because tiny samples provide too little signal.

Free checks stop at 2,000 characters, roughly 400 to 500 tokens. That is fine for an email or a few paragraphs, not a full paper. Sapling also explicitly warns that no detector should be used alone to decide who wrote a text.

The API is the real reason to choose it. New API keys include a free quota, while paid use starts at $0.005 per 1,000 characters. Most casual users will prefer Clever or QuillBot, though Sapling suits people testing a content-review workflow.

Best forDevelopers or reviewers who want token-level signals plus an optional detection API