Text Studio · Windows 10 and 11
Check spelling and grammar without uploading a word
Press Check in Text Studio and every mistake in your text gets a colored line under it: red for spelling, blue for grammar, amber for style. The panel beside it explains each one and offers fixes you apply with a click. The checker is Harper, an open-source grammar checker that runs on your PC, so your writing never leaves it.
How to check your text
- 1
Open the checker
In Text Studio, type or paste your text, or Open a text file, then press Check.
- 2
Choose your English
Pick English (US), (UK), (Canada), (Australia) or (India) at the top of the panel, so colour and color are judged right.
- 3
Go through the list
Each card says what is wrong. Click a card to jump to it in the text, or put the cursor in an underlined word to bring up its card.
- 4
Fix or skip
Click a suggested fix to apply it. Fix all … like this fixes every identical mistake at once, Ignore skips one, and Add to dictionary teaches it a name or a word it does not know.
What it catches
Harper checks with hundreds of rules written for English, plus a dictionary. In our test sentences it caught, among others:
- Misspellings such as tomorow and freind, with the likely words to replace them, and spellings from another English than the one you chose: colour in American English.
- Typos such as teh for the, and missing apostrophes, as in dont.
- Repeated words: a a test, and and.
- Mixed-up words: Their going for They're going, could of for could have.
- Agreement and usage: we was, its a for it's a, alot for a lot.
- Style: wordy and redundant phrases.
Each card names the kind of mistake, and the chips at the top of the panel (Spelling, Grammar, Style) show only one kind when the list is long.
What it does not do
Harper is a rule-based checker, not an AI writer. It does not rewrite sentences, change your tone or judge whether an argument makes sense, and like every checker it misses some mistakes and questions some correct sentences. In the same test it let it rain (for it rains) and better then (for better than) through. Read your text once yourself before it matters.
It checks English only. Text in other languages gets marked as misspelled, so check a mixed-language document a part at a time, or Ignore the foreign words.
Private by design
Online checkers and browser extensions send what you type to their servers to check it. Text Studio's checker runs inside Octoolo on your own computer: it loads once when you first press Check and then works with no connection at all, so contracts, medical notes, cover letters and unpublished work stay with you.
It checks again a moment after you stop typing, and the lines move with your edits in between. Long texts are fine: a 100,000-character document was checked in under two seconds in our test, and up to 400,000 characters are checked at a time. Words you add to your dictionary are kept on your PC, listed under Your dictionary at the bottom of the panel, where you can take any out again.
Questions, answered
Is it as good as Grammarly?
It is a different kind of tool. Harper catches common spelling and grammar mistakes quickly and privately, but it does not rewrite sentences or suggest tone changes. If you need those, an online service does more; if you need your text to stay on your PC, this does.
Does it work offline?
Yes. The checker comes with Octoolo and runs on your computer, with or without a connection.
Which languages does it check?
English only, in its American, British, Canadian, Australian and Indian forms.
Can I check a Word document?
Text Studio works on plain text: paste the text from your document, or open a .txt or .md file. Fix it, then paste it back.
Why is a name underlined?
It is not in the dictionary. Click Add to dictionary on its card and it will not be marked again.
Grammar checker, and 16 more apps.
Download for Windows7 days free, then from $3.99 a month for all 17 apps. Windows 10 and 11.