Contentor

Free · no sign-up

Free AI detector

Find out whether a text was written by a person or generated by ChatGPT, Gemini or another AI, with the reason behind each signal.

0/2,000 words

Quick answer

An AI detector estimates how likely it is that a text was generated by artificial intelligence. Contentor's detector combines an AI model's reading with two signals measured in the text itself: typical AI phrases and how much sentence length varies. It is free, needs no sign-up and explains every signal. No detector is definitive proof.

Updated October 6, 2026

Tool facts

Price
Free
Sign-up
Not required
Text length
50 to 2,000 words
Usage limit
12 checks every 10 minutes
Languages
English, Portuguese, Spanish and more
Output
AI probability from 0 to 100%, verdict, signals and AI phrases
Accuracy
An estimate: evidence, not proof
Privacy
Contentor does not store your text

How to use it

  1. 1

    Paste the text

    Paste at least 50 words. The more text, the steadier the result.

  2. 2

    Run the check

    Click Detect AI (or Ctrl + Enter). It takes a few seconds.

  3. 3

    Read the signals

    See the probability, the verdict and what weighed in: typical AI phrases, sentence rhythm and the model reading.

  4. 4

    Decide with context

    Treat the result as evidence. If the text needs to sound more human, send it to the humanizer in one click.

Tips for better results

  • Check 150 words or more

    Short passages carry few signals and give unstable results in any detector.

  • Never accuse someone over a number

    Detectors make mistakes, including on very formal human writing or text by non-native speakers. Talk to the writer and ask for drafts first.

  • Look at the signals, not just the percentage

    The phrases found and the sentence rhythm show exactly what to edit.

  • Test your own text before publishing

    If your text reads like AI, it probably reads as generic to your audience too. Add your own examples and data.

Frequently asked questions

Is the AI detector reliable?

It gives an estimate, not proof. Every AI detector makes mistakes both ways: it flags human text as AI (false positives) and misses edited AI text. That is why Contentor shows the signals behind the score, so you can judge with context.

Does it detect ChatGPT, Gemini and Claude?

It looks for patterns common to text generated by language models such as ChatGPT, Gemini and Claude, not for the fingerprint of one specific model. It cannot tell which AI wrote the text.

How many words do I need?

At least 50 and at most 2,000. Below 150 words, the result is less stable.

What are typical AI phrases?

Stock phrases that language models use often, such as "furthermore", "it is important to note" and "in today's digital landscape". People use them too; what stands out is how densely they appear.

What does sentence length variation mean?

It measures how much sentence length changes across the text. Unedited AI text tends to use sentences of similar length; human writing mixes short and long ones.

Does Contentor keep the text I check?

No. The text is sent to an AI model only for the analysis and is not stored by Contentor. Avoid pasting personal or confidential data.

Guides to go further

More free tools

See all tools

From draft to published article

Detection is the end of the line. In Contentor, articles start with a brief, a structure and internal links built for readers, for Google and for AI assistants. Try it free for 3 days.

Try Contentor for free