Free Online Grammar Checker

What it checks

Common misspellings, capitalization, spacing around punctuation, a/an usage, repeated words, frequently confused words (then/than, their/there, its/it's), “could of”-type errors and basic subject–verb agreement — using American English conventions. It is rule-based, so it does not catch every error, such as tense shifts or run-on sentences.

Common errors it catches

Its/it's, your/you're and their/there/they're mix-ups; then/than after comparisons; “could of” instead of “could have”; basic subject–verb agreement (“she don't,” “they was”); a/an before vowel sounds; repeated words (“the the”); a lowercase “i” and sentences that start without a capital letter; extra spaces and missing spaces after punctuation; and frequently misspelled words such as “definitely,” “separate” and “receive.”

The checker is rule-based and runs in your browser. It does not catch every mistake — inconsistent tense, comma splices and missing articles still need a careful read.

Each issue shows the original text, the suggested fix, the type of error and a one-line explanation, followed by a fully corrected version you can copy.

How to proofread with a grammar checker

Run the checker after you finish writing, not while drafting — stopping to fix commas breaks your flow. Review suggestions one by one instead of accepting everything: a checker may not know your intended meaning, a name, or a deliberate stylistic choice.

Then read the corrected text once more from start to finish. Grammar tools are good at mechanics but cannot judge whether your argument is clear or your facts are right.

Learn from the explanations

If the same error appears several times, it is worth learning the rule. Keep a short personal list of your most common mistakes and check for them in future drafts; over time you will need fewer corrections.