Te-form checker
て-form is where most conjugation mistakes start: the ぶ／む／ぬ group takes んで, く becomes いて but 行く is 行って, and する verbs go their own way. Paste a sentence and every te-form in it gets checked — with the rule behind the fix.
What this page checks
- ·godan て-form: く→いて, ぐ→いで, す→して, つ／る／う→って, ぶ／む／ぬ→んで
- ·The irregulars: 行く→行って, する→して, 来る→来て
- ·て-form compounds: ～ている, ～てある, ～てしまう, ～てもいい, ～てから
- ·Whether the て-form was the right form to use at all
What you get back
Here is a real example. Every correction names the grammar point, because knowing which character changed teaches you nothing about the next sentence.
You wrote
子供の頃、公園でよく遊びていました。
Corrected
子供の頃、公園でよく遊んでいました。
When I was a child, I often played in the park.
1 correction — and why
遊びて → 遊んで
遊ぶ is a godan verb ending in ぶ, and the ぶ／む／ぬ group takes んで, not びて — 遊ぶ→遊んで, 読む→読んで, 死ぬ→死んで. The びて shape comes from the polite stem 遊び, which is not what て attaches to here.
More natural
子供の頃、よく公園で遊んでいました。
Why this exists
Lang-8 shut down. HiNative answers arrive hours later, if at all. italki costs money per correction. Meanwhile the question “is this sentence right?” is the single most common thing a Japanese learner needs answered, and it needs answering in seconds, not tomorrow.
This checker corrects particles, conjugation, word order, politeness register, and word choice, then explains each fix in plain English and estimates the JLPT level of what you wrote. Every check produces a permanent page you can link, bookmark, or send to whoever asked.
What it will not do
It checks Japanese sentences and nothing else — it is not a translator, a chatbot, or a homework machine. Input has to be in hiragana, katakana, or kanji, and one sentence at a time.
Checking more than one sentence?
A free account keeps every check in one place and shows which grammar points you keep getting wrong — so the same particle mistake stops coming back instead of being re-corrected every week.
The checker itself stays free and unlimited either way. No card, no trial.