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Free English Grammar Checker

Paste any English sentence, email, or paragraph and get an instant grammar check with clear explanations. The checker finds verb tense errors, subject–verb agreement mistakes, preposition slips, missing articles, and word-order problems — and tells you why each one is wrong, so the same mistake doesn't come back tomorrow.

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PromGee for Windows · $25 · one-time payment

Understand the rule behind the correction

The tool suggests changes to your text. PromGee offers focused quizzes and AI explanations to practice the underlying pattern. Review the context and keep practicing; improvement varies by learner. AI features in the paid Windows desktop app require internet and have unlimited usage. The free website tools are separate and have usage limits.

  • Focused quizzes: grammar, tenses, prepositions, articles and more
  • AI explanations in 40+ languages
  • Lifetime license: $25 one-time payment, unlimited use, no subscription
Get PromGee — $25 lifetimeSee what's included

What This Free Grammar Checker Finds

  • Verb tense errors — “She go to school yesterday” → “She went to school yesterday”
  • Subject–verb agreement — “He don't know” → “He doesn't know”
  • Preposition mistakes — “I'm good in English” → “I'm good at English”
  • Article errors (a, an, the) — “I have car” → “I have a car”
  • Word form and countability — “buyed a new books” → “bought some new books”
  • Sentence structure and word order problems

How the Online Grammar Check Works

  1. 1

    Paste or type your English text

    Write a sentence, an email paragraph, or an essay excerpt. A few sentences to a few hundred words works best.

  2. 2

    Click “Check Grammar”

    The checker analyzes tenses, agreement, prepositions, articles, and word order in seconds — no sign-up and no credit card needed.

  3. 3

    Read the why, not just the fix

    Every correction comes with the grammar rule behind it, so you learn the pattern instead of memorizing the fix.

Example: Before and After

What you wrote

She go to school yesterday and buyed a new books.

Corrected

She went to school yesterday and bought some new books.

Three errors caught at once: past tense (go → went), the irregular verb form (buyed → bought), and countable noun grammar (a new books → some new books). The checker shows the rule behind each fix, just like it will for your own sentences.

Common grammar mistakes the checker catches

These are errors English learners make again and again. Paste your text into the checker to find the same kinds of mistakes in your own writing.

  • Written: She don't like coffee.

    Corrected: She doesn't like coffee.

    With he, she and it in the present simple, use "does" and "doesn't", not "do" and "don't".

  • Written: I have seen him yesterday.

    Corrected: I saw him yesterday.

    Words for finished time, like "yesterday" or "last week", need the past simple, not the present perfect.

  • Written: He is engineer.

    Corrected: He is an engineer.

    A singular countable noun needs an article. Use "a" or "an" for jobs and roles.

  • Written: I am living here since 2019.

    Corrected: I have been living here since 2019.

    For an action that started in the past and continues now, use the present perfect (continuous) with "since" or "for".

  • Written: Can you tell me where is the station?

    Corrected: Can you tell me where the station is?

    Inside an indirect question, use normal statement order: subject first, then the verb.

  • Written: I look forward to hear from you.

    Corrected: I look forward to hearing from you.

    In "look forward to", "to" is a preposition, so the next verb takes the -ing form.

Grammar Checker FAQ

Is this English grammar checker really free?

Yes — no account or credit card is required. Per IP, the grammar checker allows 10 requests per 60 seconds; each rewriting tool allows 12 requests per 60 seconds. Wait before retrying if you reach a limit.

Does it explain the grammar rule behind each correction?

Yes. Each mistake shows the suggested fix, the rule that applies, and a short explanation written for English learners, so you stop repeating the same error.

What kinds of mistakes does it detect?

Verb tenses, subject–verb agreement, prepositions (in, on, at), articles (a, an, the), word forms, spelling, and basic sentence structure. It is tuned for the mistakes English learners actually make, not just native-speaker typos.

Can I use it on my phone?

The online checker works in modern browsers on Windows, Mac, Android and iPhone and requires internet. PromGee is a separate Windows app that keeps progress locally; its AI features also require internet.

Is my text stored or shared?

Submitted text is sent to the AI provider to generate results. This is online processing, separate from the Windows app's local progress storage. Provider handling is governed by its own privacy terms.

Keep Learning: Related Grammar Guides