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Grammar Checker AI

For learners and writers of Japanese

Japanese grammar checker for particles, kanji and politeness

Paste Japanese text, from a class assignment to an email to a colleague. It comes back corrected, with each main fix explained in English: the particle, the conjugation or the kanji that was wrong.

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  • Particles
  • One politeness level
  • Kanji conversion mistakes
Language
Depth
0 / 3,000 words

Corrected text

Paste your text and press Check grammar. The corrected text and the main fixes appear here.

At a glance

This Japanese grammar checker corrects particles, verb and adjective conjugation, mixed politeness levels, kanji conversion mistakes, okurigana and Japanese punctuation. Paste up to 3,000 kanji and kana (each counts as one word), keep Japanese selected, and get the corrected text with up to 12 main fixes explained in English. Signing up is free; checks use purchased credits at 1 credit per word.

Language
Japanese; です・ます or plain style kept as you write it
Checks
Particles, conjugation, politeness, kanji, okurigana, punctuation
Counting
Each kanji or kana counts as one word
Explanations
In English, up to 12 main fixes per check
Price
1 credit per word, 20-credit minimum; $0.08 to $0.20 per 1,000 words
Account
Free to sign up; checks use purchased credits

What the Japanese check looks at

  • 01

    Particles

    は or が, を, に or で, へ: a particle that does not fit its verb is corrected, with the reason in English.

  • 02

    Conjugation

    Verb forms and adjective endings, such as 楽しかったです in place of 楽しいでした.

  • 03

    One politeness level

    A text that switches between です・ます and the plain style is made consistent with the style it uses most; keigo is kept where you use it.

  • 04

    Kanji conversion mistakes

    Wrong homophones picked while typing, such as 以外 for 意外, and missing or extra okurigana.

How to check Japanese grammar

  1. 01

    Paste the Japanese text

    Kanji, hiragana and katakana all come through; each character counts as one word for the price.

  2. 02

    Keep Japanese selected

    Choose proofread to fix errors only, or polish to make awkward sentences read more naturally too.

  3. 03

    Read the fixes

    Each main fix quotes the Japanese, shows the correction and explains the rule in English.

Common Japanese mistakes, with corrections

These are among the errors the Japanese checklist covers. Each line shows the mistake, the correction and the reason:

  • 学校を行きます → 学校に行きます (に or へ marks the place you go to)
  • 誰は来ましたか → 誰が来ましたか (a question word as the subject takes が)
  • 楽しいでした → 楽しかったです (an い-adjective carries the past tense itself)
  • 静かの部屋 → 静かな部屋 (a な-adjective takes な before a noun)
  • 以外と簡単だった → 意外と簡単だった (意外 means unexpectedly; 以外 means except)
  • 見れる → 見られる (the shortened form is common in speech but avoided in formal writing)
  • 行きました。楽しかった。 → 行きました。楽しかったです。 (keep one politeness level)

Politeness, keigo and style

The checker keeps the style your text uses. If most sentences end in です or ます, a stray plain-style sentence is made polite; if the text is in the plain style, it stays plain. Keigo you use, such as いらっしゃる or 申し上げる, is kept, and wrong forms are corrected where the checker recognizes them.

For an important letter to a client or a job application, have a fluent speaker read the result as well: the right level of keigo depends on relationships the checker cannot see.

Check these yourself

Four checks you can do before you paste:

  • Read each particle together with its verb: に行く, を食べる, で働く.
  • Check that past-tense い-adjectives end in かった.
  • Look again at every kanji your keyboard chose for you.
  • Pick です・ます or the plain style and keep it to the end.

More checkers

Japanese grammar checker FAQ

Are the explanations in English or Japanese?

In English. The corrected text stays in Japanese, and each of up to 12 main fixes quotes the Japanese words, shows the correction and gives a short reason in English, for example "に marks the destination".

Does it change kana to kanji?

Not when both are correct. It fixes kanji that are wrong, such as conversion mistakes, and missing or extra okurigana, but it is told to keep correct hiragana and kanji exactly as you wrote them.

How is Japanese text priced?

Kanji, hiragana and katakana count as one word each, and punctuation is not counted, so a paragraph of 400 kanji and kana costs 400 credits. Every check costs at least 20 credits, and up to 3,000 kanji and kana fit in one check.

Is this Japanese grammar checker free?

Signing up and reading the mistake list on this page are free. Checks use purchased credits at 1 credit per word; new accounts start with no credits, and packs start at $4.99.

Check your Japanese before you send it

Packs start at $4.99 for 25,000 credits, about 25,000 kanji and kana. Signing up is free.

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Last updated October 23, 2026

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