Introduction
An aiチェッカ is a tool that estimates whether a text was written by a generative AI such as ChatGPT. To choose one, look for clear support for your language, test it on writing you know is human, and never rely on a single score. Below is a ten-minute method for doing that, plus the mistakes that most often lead people astray.
What does an aiチェッカ actually measure?
It measures resemblance, not authorship. Most tools look at how predictable a text is: word choice, sentence rhythm and how smoothly the ideas connect. Generative AI tends to write very evenly, so very even text scores as “likely AI.”
Three things follow:
- A score of “70% AI” is a probability. It does not mean 70% of the text was machine-written.
- Edited AI text often passes as human, and tidy human writing is sometimes flagged.
- Tools lag behind new models, so a result that was reliable last year may be less reliable now.
Why is checking Japanese and Dutch text harder?
Many detectors were built and tested mainly on English [VERIFY]. Japanese and Dutch each add their own difficulties.
Japanese. There are no spaces between words, so the tool must split the text first, and tools do this differently. Kanji, hiragana, katakana and Latin letters often share a sentence. Business writing and polite registers follow fixed patterns, which can make careful human writing look “too regular.”
Dutch. Long compound words and a mix of formal and informal registers can behave differently from English. Many Dutch writers also use English terms in everyday work, which can confuse a tool tuned for one language. An ai checker that does not state Dutch support deserves caution.
Both languages. Very short texts give unstable results. A few lines are not enough for any tool.
These language points come from my own reasoning about how such tools behave, not from a published study.
How do you test an aiチェッカ before trusting it?
Run a three-sample check. It tells you more than any feature list.
- Prepare three samples of at least 300 words in your language. Sample A is something you wrote yourself some time ago. Sample B is raw AI output. Sample C is the same AI output after you rewrote it in your own words.
- Paste each into the [aiチェッカ]([TARGET URL]) you want to evaluate. Do not paste confidential material, and read the privacy terms first.
- Compare the pattern. A useful tool scores A low, B high and C somewhere in between.
- Repeat with a second tool. If two tools disagree widely, treat the result as inconclusive.
- Judge the tool before the text. If Sample A comes back as “AI,” the tool is unreliable for your kind of writing, and its verdict on someone else’s work means little.
Example: you check a 500-word cover letter. One tool says 85% AI, another says 20%. Neither number settles anything. What helps is the writer’s draft history, their notes, or a short conversation about the content.
What should you compare when choosing a tool?
| What to check | Why it matters | Warning sign |
| Language support | Tuning for your language affects accuracy | Supported languages not listed |
| Minimum length | Longer samples give steadier results | Accepts one sentence without a warning |
| Explanation | Highlighted passages let you judge for yourself | A single bare percentage |
| Privacy | Submitted text may be stored or reused | No privacy policy |
| Claims | Honest tools state their limits | “100% accurate” or similar guarantees |
The same table works whether you are comparing a Japanese tool with an international ai checker or two tools from the same country.
What mistakes do people make?
- Treating the score as proof. It is an estimate. Use it to decide where to look closer, not to accuse anyone.
- Checking only the whole text. Test sections separately. One flagged paragraph means something different from a fully flagged document.
- Ignoring genre. Formal letters, academic abstracts and product descriptions often score high even when written by hand.
- Using one tool and stopping. A single result cannot show whether the tool itself is reliable.
- Skipping the human read. Vague claims, generic examples and invented sources are often clearer clues than a percentage.
Conclusion: use an aiチェッカ as one clue among several
A good AI checker gratis helps you decide what deserves a second look, and it lets you check your own writing before you submit it. It cannot read intent or prove who wrote a text. Choose one that supports your language, test it with your own samples, compare at least two tools, and read the text yourself. If a result matters for a grade, a job or a contract, support it with drafts, version history or a conversation.
FAQ
Are AI detectors accurate for Japanese and Dutch?
Accuracy varies a lot by tool and by text. Many tools were developed mainly for English [VERIFY], so test with a sample you know is human-written before relying on any result.
Can a detector flag text I wrote myself?
Yes. Formal, polite or template-like writing is flagged more often. If it happens, keep your drafts, notes and edit history as evidence of your process.
Can edited or translated AI text be detected?
Often not reliably. Rewriting, mixing in your own sentences or translating can all lower the score. A low result does not prove a text is human-written.
