LanguageTool

Grammar can be complicated, and that's true for all languages. As you're learning a new language — or even writing in your mother tongue — it's not at all uncommon for your sentences to flounder because of some grammatical error, be it an unwitting one or not.

Considering that even natives can have some trouble when writing in their own language and that those learning a new tongue tend to make mistakes, trying out a grammar checker wouldn't be a bad idea. LanguageTool provides a Windows app that can help you improve your writing, giving you real-time corrections and style suggestions in its simple-to-use text editor.

Grammar checkers have become quite popular in the last few years, and it's easy to see why. Considering that many of them offer browser extensions and web apps, this app's offer as a standalone program is most interesting.

In essence, you can use this as you use any text editor, treating the active suggestion feature as a bonus: feed your writing into it, and it'll check and notify you if any irregularities are found.

The main reason someone would use standalone software like this — in place of a browser extension or web app — is simply owed to convenience. You no longer have to rely on your browser to make use of the checker's capabilities: the standalone app features all of them, serving to boost your productivity.

The program had no trouble picking up on the more conventional grammar errors, suggesting modifications right away. Even when it came to more complex sentences, we found its advice to still be quite helpful, though you can't fully rely on it in such cases.

If there's a word you often use that is correct, but the app keeps flagging it, there's a Personal Dictionary feature to have the program omit recommending changes to words of your choosing.

As for languages other than English, the app could not correct text in the Japanese language, even though it claims to support it. We tried inputting some passages in German and Arabic, and the app was quick to offer suggestions for those languages. 

LanguageTool can be reliably used by just about anyone to improve their writing style and consistency: it's a nice text editor, and the fact that it can suggest grammar changes the way it does is a neat bonus to have.