Dear J:

You wrote:

I would like to see a “Compliment vs. Complement” section at https://englishplus.com/grammar/00000160.htm#C. That mistake drives me crazy for some reason.

Thanks,
Joey

That is in our Spelling Slammer program which is part of Grammar Slammer Deluxe or as a separate e-book. There are many other similar words in that. That is not online. I hate to sound too commercial, but you might want to think about buying it. In the meantime, this is what we wrote:

Complement or Compliment?
Complement is something that makes complete. It can also be used as a verb to mean “to make complete.” It is related to the word complete; therefore, the letter e follows the pl.
The adjective form is complementary.

Compliment is a favor or words spoken expressing admiration. It can also be used to as a verb to mean “to speak highly of.” It is related to the word comply; therefore, an i follows the pl.
The adjective form is complimentary. In modern usage, complimentary often means “free, with our compliments.”

That definition for the grammatical term complement is found at https://englishplus.com/grammar/00000075.htm .
I hope this helps.