A grammar checker for language learners that explains every fix

What the grammar coach does

The grammar coach is LingunAI’s AI grammar checker for language learners. You paste up to 5,000 characters, let LingunAI detect the language or pick it yourself, and choose the kind of writing it is. The check returns:

• Grammar issues, each described in plain language.
• Spelling and misused-word issues, in a separate list, so grammar problems don’t get mixed up with wrong or misspelled words.
• A score from 0 to 100 for the text as a whole.

Then “Rewrite” turns the check into a lesson. You get three things:

• A corrected version that fixes the issues.
• An enhanced version in the writing style you chose.
• A list of changes, each with the reason it was made.

A check costs 1 credit, and a rewrite costs 1 more.

Writing styles

The style tells the rewrite what tone to aim for:

Who it’s for and when to use it

The grammar coach suits learners who write: an email to a colleague in German, an essay for a Spanish class, a message to a host family in Italy. It’s most useful from about A2 up, once you can write a few connected sentences, and it stays useful at C1, where the remaining mistakes are the subtle ones.

Writing deserves as much attention as reading. Paul Nation’s “four strands” framework treats meaning-focused output, using the language to say something you mean, as one of four equal parts of balanced learning, alongside meaning-focused input, language-focused learning and fluency development. Checking what you write closes the loop: you produce, see exactly what went wrong, and fix it while the sentence is still fresh.

Tips for getting the most from it

• Write about what you read. Summarize a story or article you’ve just read in five or six sentences, then check the summary. You reuse fresh vocabulary, and the check shows whether you used it correctly.
• Write first, check after. Draft the whole text before you check it. Stopping after every sentence breaks your train of thought, and each check costs a credit.
• Try the fix yourself. Read the issue list, correct the text on your own, then run Rewrite and compare your version with LingunAI’s.
• Read the reasons, not just the result. The list of changes is where the learning is. If the same reason keeps coming up, that’s the rule to study next.
• Match the style to the real situation. An Email rewrite and a Message rewrite of the same text should sound different.
• Treat the score as a signal, not a grade. It’s a quick read on one text, useful for seeing which drafts need the most work.
• Turn repeat mistakes into cards. When the same word trips you up twice, make a card for it by hand in your flashcards.

How it connects to the rest of LingunAI

When you want to understand a rule rather than fix one sentence, ask the AI tutor, which explains grammar with your level and native language in mind. To practice producing language in real time, try a roleplay: the AI character keeps the conversation going without stopping to correct you, then gives you corrections and more natural phrasings at the end.

Reading feeds writing, too. The words you can use correctly are mostly the ones you’ve met many times, so a summary of an AI-generated story you’ve just read makes a good first text to check.