Sentence Checker

About Sentence Checker

Sentence Checker: Real Grammar Checks, Plus Readability and Tone

This sentence checker does two different jobs and keeps them honestly separate. Grammar and style issues come from LanguageTool, a real established grammar-checking service. Readability and tone signals are calculated locally in your browser, using formulas and word lists you can actually see reflected in the results.

That split matters. A tool that pretends every check is equally deep is not being straight with you. Here, the grammar layer is genuinely strong. The tone and passive-voice checks are honest heuristics, useful as a signal, not a certified verdict.

If you searched for "sentence checker online" or "grammar and style checker," this page gives you both, clearly labeled.

Watch for this

Grammar and style checking sends your text to LanguageTool's public API, so that step is not fully private. Readability and tone checks stay local in your browser. The tone and passive-voice signals are heuristics, so they can miss issues or flag a few false positives.

What the grammar and style check actually catches

Click Check Text, and the page sends your text to LanguageTool, then keeps grammar, style, punctuation, word-choice, redundancy, typography, semantics, and capitalization issues. Pure spelling matches are filtered out on purpose, since that job already belongs to this site's own Spell Checker.

Each flagged span is highlighted directly inside your text, color-coded by category. Click a highlighted span, or a row in the issues table, to see LanguageTool's real explanation and one-click suggestions you can apply immediately.

That is a genuine grammar engine, not a canned message.

Good to know

If a highlighted span has no suggestions, LanguageTool still flagged it as worth a look, even without a specific fix. Read the message and decide whether the sentence needs a manual rewrite instead.

The readability score is a real, named formula

The score shown is the Flesch Reading Ease score, calculated from your word count, sentence count, and an estimated syllable count. Higher numbers mean easier reading. The page also labels the band in plain language, from "Very easy to read" down to "Very difficult to read," using the standard Flesch scale.

Alongside the score, you get word count, sentence count, average sentence length, and an estimated reading time. Those numbers update live as you type, before you even run the grammar check.

None of that depends on the LanguageTool call. It is computed right there in your browser.

Example

Say you are polishing a blog introduction. You paste the paragraph, watch the Flesch score and sentence stats update as you type, then click Check Text to catch grammar issues and see how many filler words or passive constructions showed up.

Tone and style signals, described honestly

The page also flags filler phrases like "very," "just," "in order to," and "at this point in time," with a running count of how often they appear. It runs a passive-voice heuristic based on common patterns like "is written" or "was reviewed," and shows a couple of matched sentences as examples.

A separate signal estimates whether the writing leans formal or casual, based on contractions, casual markers, formal connector words, and long sentences. All three of these are labeled as heuristics because that is what they are. They can miss things, and they can occasionally flag something that is not really an issue.

Useful signal, not a final judgment.

Yes

Readability and tone checks run entirely in your browser. Only the grammar and style step sends your text to LanguageTool's API, and that is the one part of this page that is not fully local.

How the highlighted text and suggestions work together

After a check, you get two views of the same result: the text itself with issues marked inline, and a table listing every issue with its category and suggestions. Clicking a suggestion, in either view, replaces that exact span in your text and reruns the check automatically.

That loop is what makes the tool feel like an editor rather than a one-shot report. You fix an issue, see the updated score and issue count, and keep going until the text reads the way you want.

Small fixes add up fast this way.

Why the filler-word and passive-voice lists are fixed, not AI-guessed

The filler-phrase list and the passive-voice pattern are both hardcoded and visible in how the tool behaves. That is a deliberate choice. A fixed, rule-based check is predictable: you can learn what it looks for, and you can trust that the count means the same thing every time.

It will not catch every wordy phrase or every passive sentence in the English language. It catches a practical, common set, which is usually enough to notice a pattern worth fixing.

Predictable beats mysterious here.

Where this tool fits into your writing process

Use it after a first draft, when you want a real grammar pass plus a quick sense of how dense or wordy the writing feels. It fits essays, blog posts, emails, and any text where both correctness and readability matter.

It is not a substitute for reading your own work aloud, and the tone signals should not replace your own judgment about voice. Treat the score and the flags as a second pair of eyes, not the final word.

That is exactly what a good checker should be.

Related tools that fit the same writing workflow

If you are polishing text in more than one way, these are the closest matches on the site. One catches spelling specifically, one rewords a passage, and one lets you swap repeated terms in bulk.

The short version

Sentence Checker sends your text to LanguageTool for real grammar and style checking, then adds a genuine Flesch Reading Ease score and honest, rule-based tone signals computed locally. Click any highlighted issue for a one-click fix, and watch the score update as you edit.

Real checks, clearly labeled, nothing oversold.