Grammarly
Checks grammar, clarity and tone as you type in emails, documents and web forms, and helps draft and edit text on most sites.
Chrome extension
Fixes spelling and grammar in Gmail, Outlook and other web text boxes, and suggests synonyms, style changes and rephrased sentences.
Outwrite checks spelling, grammar and punctuation in Chrome wherever you write, including Gmail, Outlook, LinkedIn, Medium and WordPress. It is for people who want corrections plus help with word choice, style and sentence rewording.
Start typing in a supported text field and Outwrite marks issues as you go; click a suggestion to apply it.
Text you write is checked by the developer's service. Check its Chrome Web Store page for current terms.