Grammarly

[Georgyporky]

An advert for this keeps popping up on MN.

The blurb is "Don't let grammar errors spoil your emails!"

I would say "grammatical errors" , or "errors of grammar".

I'd accept this from a MNer, but not a programme that purports to check grammar.

Or perhaps it's a non-British program (sic) .

I would have thought that either was correct. You can say grammar errors just as you could say, eg, tennis errors. You aren't obliged to use an adjectival form.

It is American with all the Americanisms you'd expect in terms of spelling and grammar

Those ads can be a bit cringe, especially when they don’t get the grammar right themselves! It's funny how you expect a grammar tool to have its act together. I once tried using a similar program, and while it helped me catch a few mistakes, it still missed some key stuff, which was frustrating. That’s why I started checking out Become a Writer Today. They had some really helpful tips on improving writing skills, and it felt more personal than just relying on software.