This article uses Scrutiny for Mac which has a 30-day free trial.
1. select the site from the site list, or click New to add the site. Click Next.
2. Check 'Spelling' and (if you like) 'Grammar'. If your language isn't selected in the drop-down list, choose your language too. Click Next
3. Click Go for Spelling and Grammar check. You'll see a progress bar as Scrutiny scans your site.
4. When the results appear, you can sort the table by any of the columns including number of spelling and number of grammar issues. Double-click a page to open a dialogue to step through the issues with the usual stuff; suggestions and 'Learn'.