In addition to their outstanding AI machine translation, which Help+Manual has integrated for a while, DeepL now also offers Write, their AI grammar, proofreading and style assistant. Help+Manual 10 adds support for DeepL Write in the DeepL Translator plugin.

This is only available with a paid subscription. DeepL doesn't offer a free tier for this service. Please note also that Write is definitely still in quite early stages of its development, but it is already quite useful.

See Using DeepL Write in the ChatGPT & DeepL Write chapter for details.