Techlearning iconTechlearningSep 16, 2026 ~4 min source read

How four free checkers performed when tested on plagiarism and AI-written text

A practical summary of test methods and results for Grammarly, Quetext, Dupli Checker, and Plagiarism Detector, aimed at teachers who need reliable free tools for checking student work.

I Tested The Best Free Plagiarism and AI Content-Checking Sites

Share this story

Send the public story page.

Useful takeaways from this story.

Grammarly and Quetext gave the strongest, most consistent results across plagiarism and AI detection in these tests.

Dupli Checker and Plagiarism Detector worked well for short-to-medium texts but show inconsistent AI-detection scores and have usage quirks to manage.

Free limits, required accounts, and interface features differ: check word counts, cookie effects, and report formats before relying on a single tool.

The useful part

Yet these two practices-one ancient and one modem-are linked by their ability to replace true learning with copy-and-paste. Each site was tested using passages of 150-200 words on these topics: plagiarism (Wikipedia), George Washington (Wikipedia), and Romeo and Juliet (Cliffsnotes). Each site was tested using passages of 150-200 words generated by Google's AI mode on the following topics: plagiarism, George Washington, and Romeo and Juliet.

How it works

  • In our modern world, however, the ability of students to find and copy others' work is greater than ever before.
  • While there are a number of in-depth and effective paid solutions that allow educators to verify the originality of student work, there are only a few free solutions that are worth trying.
  • Best Free Plagiarism and AI Content-Checking Sites Grammarly Grammarly's free plagiarism and artificial intelligence detector tools allow users to simply paste text or upload files to be scanned for...
  • After that, users can quickly create a free account via Google, Apple, or email to continue scanning.
  • Unlike many other plagiarism sites, Quetext makes it easy to compare the free and pro offerings -- free accounts allow 2,500 words monthly, while the paid Pro account allows 100,000 words, plus deeper...

What to take from it

Artificial intelligence-generated content is a very new problem. Much earlier than that, in the first century, the Roman poet Martial used " plagiarius" to castigate another poet whom he accused of appropriating his words. Sites that characterized trial texts as substantially or highly plagiarized or passed my testing.

Example or evidence

  • With no account needed, users can check for plagiarism and content once daily.
  • Interestingly, six sites which had passed near-identical plagiarism testing three years ago failed the most recent testing and have been excluded.
  • Check out T&L contributor Erik Ofgang's article 10 Ways to Detect AI Writing Without Technology.
  • Grammarly's AI detector delivered a perfect result, correctly identifying all three texts as 100% AI.

Details worth keeping

Read on for the best free online plagiarism and content checkers. Quetext With a clean, well-designed interface, it's a pleasure to use Quetext. After the first free search, you'll need to create a free account.

Related coverage

  • Habr: Площадки перестали пускать машинный текст самотёком.
  • Techbuzzireland: So ChatGPT Zero is this tool everyone's talking about.
  • Medium: Artificial intelligence has changed the way people write. Today, AI writing assistants can brainstorm ideas, create outlines, rewrite… Continue reading on Medium »

More context around this story.

Написал детектор ИИ-текста на 13 правил и прогнал 59 своих статей: сумма баллов не забраковала ни одну
Habr iconHabrSep 2, 2026

Написал детектор ИИ-текста на 13 правил и прогнал 59 своих статей: сумма баллов не забраковала ни одну

Площадки перестали пускать машинный текст самотёком. Habr проверяет публикации автоматически, а Кевин Индиг пишет о том, что платформы строят anti-slop-системы — механизмы подавления массового низкокачественного ИИ-контента. Дальше обычно следует совет писать хорошо, и на этом разговор заканчивается. Мне нужно было про

Loading more related stories...

Keep reading in the app

Open the app view to save this story, compare related coverage, and continue from the same source.

Open in app