LanguageTool is an open-source spelling and grammar checker for Chrome, Firefox, the desktop (via Java) and more.

The browser extensions enable checking the text you’re entering a web text box, or any other selectable text on a web page.

The system works much like other spell checks. Enter text, click the LanguageTool icon and it instantly displays a report listing any issues. Browse the list, click any corrections you’d like to accept and it’s updated in the source text.

If you don’t want to apply a particular rule, you can turn it off from the report with a single click. Similarly, you’re able to add special words to a personal dictionary so they won’t be flagged as misspelled.

LanguageTool isn’t as interactive as some of the competition. Errors aren’t highlighted in the text as you type, for instance, Grammarly-style.

Choose and click a correction and (sometimes) it’s updated in the source

On the plus side, LanguageTool works with 25+ languages, including English, Spanish, French, German, Polish, and Russian. Even if you’re just using English, it supports variations including American, British, Australian, New Zealand, South African and Canadian.

The browser extensions have at least a theoretical privacy risk, as they check your text by sending it to https://languagetool.org. This also introduces practical issues, as it means you can only use the system when you’re online.

The desktop version processes the text itself, allowing it to work offline and ensuring no data leaves your system. It’s also more interactive, as you can type in a text area and see a report updated in real time.

What you don’t get on the desktop is any other significant integration with your system. You can’t use it in Office, and it won’t open Word or other complex formats for checking– the best you get is reports on the contents of the clipboard and plain text files.

Overall, LanguageTool does a good job for an entirely free and open-source product, and its multi-language support is a highlight. Give it a try.

LanguageTool is available for Chrome, Firefox, the desktop, Google Docs and more.