The other day, I looked up for an online spell checker. I found out about Grammarly. At first, I was a bit concerned because it offered me to install a browser extension, which I'm generally cautious about.
I decided to give it a try, and it's awesome!
In every web forms, it checks for typos and grammar. And it works great here, so now it spells checks all my posts.
Very useful, as I'm not a native English speaking person.
So give it a try, you won't regret it I guess.