Not perfect but works well. It turns all text elements into input fields, which forces Chrome to apply spellcheck. This is great because it's a trusted spellcheck engine, however, this breaks the UX so it would have been nice to see a more refined interface for switching it on/off. The privacy policy is also not listed, it would be nice to know that the plugin does not sell or store my data; I would be happy to pay a few bucks for this tool provided it does the above things.
Instant spell-check on any web page
This Chrome extension allows users to check the spelling directly on the web page, identify and fix errors, and edit typos directly in the web page using the Google Chrome spell checker