Language Tool
LanguageTool detects many errors that a simple spell checker cannot, such as grammar issues, commonly confused words, and punctuation oversights.
Everyone should install it
This is a general use tool, that you install in your browser to help you with emails and checking websites.
Everyone should remove obvious grammar mistakes
https://languagetool.org/As part of maintaining a good standard in our work, we should look out spelling or grammar mistakes as we work.
This tool does this for you.
More info here
Use if for pre-launch Quality Assurance
You can copy and paste a whole page into LanguageTool, and it will check for grammar and spelling mistakes.