Time to say another Chrome extension I use - Grammarly - shown as the green dot with a white arrow. Whatever I type while using Chrome, including these blog entries, is automatically checked for spelling and grammar. Again, I use the free level of the extension, and haven't seen the need to go "Pro".
If there doesn't seem like there is much information about configuring or using this Chrome extension, how can you say much about a spelling and grammar checker that runs in the background? Just click of whatever it flags for options to correct it. The biggest issue I see flagged is an "unnecessary comma" (I was always taught that you use a comma as if during narrating aloud you have a pause), but you can tell Grammarly to ignore each instance individually when it prompts.