Checking if a word is spelled correctly is easy. It is providing high-quality suggestions that is hard.

▲ bluGill 6 days ago | parent | next [-]

Even that is hard since there are many words where a mispelling is a valid different word.

▲ Finnucane 6 days ago | parent | prev | next [-]

As a copyeditor/proofreader, the number of times over the years I've had to fix the low-quality (i.e, wrong) suggestions is quite large. ("he had a small plague on his desk" remains a favorite.)

	▲	cratermoon 6 days ago \| parent \| next [-]
		`I have a spelling checker It came with my PC It highlights for my review Mistakes I cannot sea. I ran this poem thru it I'm sure your pleased to no Its letter perfect in it's weigh My checker told me sew.` https://www.thoughtco.com/spell-checker-poem-by-mark-eckman-...
	▲	aidenn0 5 days ago \| parent \| prev \| next [-]
		"He looked in the [car's] grove department" is still my favorite.
	▲	KineticLensman 6 days ago \| parent \| prev [-]
		One of my favourites was 'rouge elephant'.

▲ DJBunnies 6 days ago | parent | prev [-]

Having written a spellcheck, maybe 20 years ago for school, this is accurate.