Kimi AI Detector

This is a free Kimi AI detector for English text. Paste 100 words or more into the checker above and V4, our current engine, checks the passage for AI-writing patterns, including those it learned from Kimi output. You get a score from 1 to 99, a stability range and one of three verdicts, Likely human-written, Uncertain or Likely AI-written, plus a line showing how often human writing of the same length was wrongly flagged. Nothing to install, no account, and your text is not stored.

Kimi writing was part of V4’s training, and when we tested the frozen engine on new Kimi texts it caught 207 of 209 of those with 150 words or more. The rest of this guide covers how to use the Kimi checker well, what a result does and does not tell you, and the test behind the numbers.

Can a Kimi AI detector tell you that Kimi wrote something?

It can tell you that a passage reads like AI writing; it cannot tell you that Kimi wrote it. V4 learned from nine model families together, and Kimi writes in a register that overlaps with Claude, Qwen and other assistants, so a high score describes the text rather than the tool behind it.

• Yes: it scores English passages of 100 words or more and gives a clear verdict.
• Yes: it catches unedited Kimi output very reliably, 99.04% at 150 words or more in the sealed test.
• No: it does not name Kimi or any other model as the author.
• No: it does not prove who wrote a text. Edits and translation change the score.

What the Kimi AI checker looks at

V4 is one fine-tuned transformer text classifier. It reads a passage through overlapping windows, combines them into a single internal value and maps that onto the 1–99 scale. Its training data covered texts from nine model families, Kimi among them, and a large body of human writing from 2021 or earlier, before chat assistants were in everyday use. After training it was frozen, and nothing changes based on what people check.

It does not compare your text with a database, search the web or judge sentences one at a time; the score describes the whole passage. If you want the technical picture, how the detector works sets it out.

The score is not the share of the text written by AI, and it is not a probability. A result alone does not prove who wrote a text.

Kimi and long documents

Kimi is often used for long work: summarising papers, drafting reports or answering questions about a large file. That kind of output tends to be long, and length helps a detector. In the sealed test, Kimi texts of 150 to 299 words were all caught, and the longer bands stayed close to the top at 98.61% (300 to 599 words) and 98.55% (600 words or more).

When you check a long Kimi-assisted document, paste the parts you have a question about, at least 150 words each, rather than one huge block. A long document that mixes human sections with model sections gives one blended score, which can hide the passage that matters.

How to check Kimi text

1. Use the original wording. Copy the text as submitted, before any editing.
2. Paste 100 words or more into the box at the top; aim for 150 or more where you can.
3. Run the check and read the verdict with its score and stability range.
4. Check the evidence line for how often human writing of that length reached the same zone.
5. Weigh it with other evidence: drafts, notes, sources and the writer’s own account.

You can compare up to 3 passages side by side, and save any result as a PDF.

Reading a Kimi detector result

Every result sits in one of three zones. From 1 to 34 the passage looks like most human writing of its length. From 35 to 64 it is Uncertain: higher than typical human writing, but under the AI line. From 65 to 99 it is Likely AI-written, with a Moderate signal chip up to 84 and a Strong signal chip from 85.

That line is 65 for every length. Behind it, each length band has its own frozen internal threshold, and the scale is mapped so that 65 is that threshold. The stability range tells you how far the score shifts when the source families behind the score map are resampled; the zone itself is decided by the frozen line. Understanding results goes through the card line by line.

For Kimi in particular, expect a raw text to score high. A human-zone or Uncertain result on a Kimi text most often means it was edited or is short, and it is not evidence that a person wrote it.

How V4 learned from Kimi text, and how well it detects it

V4 was trained with Kimi writing in its data, alongside eight other families. To see how much that helps on texts the engine has never met, we scored the frozen engine once, on 17 October 2026, on new Kimi texts that had been held back from training entirely.

We prompted Kimi between 10 and 13 October 2026 for 35 kinds of writing, including speeches, recipes, product listings, op-eds and short fiction, in 6 registers, and anchored half of the prompts in genuine human writing so the subjects were realistic. The texts came through the Together API, with Kimi treated as a strong-tier model: a quarter of its texts were written with reasoning on and the rest with it off. The prompts, task types and styles were the same as for every family. Only the answer a reader would see was scored, after thinking traces and close duplicates were removed.

What the test found:

• One version, a clear result. 207 of 209 texts of 150 words or more were caught (99.04%), and 39 of 40 at 100 to 149 words (97.50%).
• The short band was the weakest, as for most families: 97.50% at 100 to 149 words, then 100.00%, 98.61% and 98.55% for the longer bands.
• Without Kimi in training. In the development test, when Kimi was withheld from training, 97.73% of its texts were still caught: its prose is well within what the engine learns from other families.
• A big step from the previous engine, which caught 37.32% of the same texts, just over a third.
• Rewriting tricks were tested on the full development set only; the worst, swapping in synonyms, still left 97.40% of AI texts caught.

See the evidence page for every family and length band, and the methodology for how the sets were kept apart.

One real example

Here is a casual email that Kimi wrote for the development set (464 words). Result: 95, stability range 92–98, zone Likely AI-written. Opening 55 words:

In a nutshell, my school didn’t handle the transition to online courses for the Covid outbreak well at all. I’m writing to you because you’re one of the few teachers who actually tried to make it work, and I wanted to give you some feedback about the whole situation. The first week was total chaos.

Edited text and human writing that gets flagged

The Kimi results describe untouched output. Summarised, reworded or machine-translated text is a different population; the sealed rates stop applying and scores tend to drop. That is why a low score on a text you suspect is weak evidence either way.

Human writing can also cross the line. In the sealed test, 4 of 2,863 human texts of 150 words or more reached 65, about 1 in 700, from sources the engine never trained on. Shorter texts were flagged more often, about 1 in 100 at 100 to 149 words. Learners of English were flagged about 3 times as often as native writers at the same lengths, and formal speeches reached the line in 17 of 931 cases. If this happened to you, what to do if your text is flagged explains how to show your process.

Using a Kimi checker fairly

Use the checker to decide what to read more closely, then rely on the writing process: drafts, version history, sources and a conversation with the writer. Never decide a grade, a contract or a complaint on a score alone, and allow extra room for short passages and for writers whose first language is not English.

Kimi AI detector FAQ

Other AI model guides

Every guide uses the same checker and reports its own family’s results. See all model guides, or compare with DeepSeek, MiniMax, the Qwen AI detector and the Claude AI detector.

Tested and written by the AI Detector Checker team. Last tested: 17 October 2026.