Harper – an open-source alternative to Grammarly

I never understood the appeal of grammar tools. If you have reached the minimum professional/academic level needed to be designated to write something, shouldn't you at least be capable of verifying its semantic "correctness" just by reading through it once yourself?

Why would you pass a writing job to someone who isn't 100% fluent in the language and then make up for it by buying complex tools?

I use it (well, languagetool) in the free version for comments on sites like this. It directly catches mistakes I make, that I'd normally only catch on re-reads. From typos, over my brain doing weird stuff, to sometimes things I simply didn't (actively) know.

As a non native English speaker/writer there are a bunch of errors I miss, no matter how much attention I pay and how much I proofread, and these tools are useful to catch those.

Have you considered that some people aren’t 100% fluent in English but still competent?

I know for example David Sparks (MacSparky https://www.macsparky.com ) uses it (or at leased used it). And he was an American lawyer and he says writing has been his passion his whole life so I assume his English is better than the average person.

People are bad at proofreading their own work. Professional writers often use third-party copy editors and proofreaders for that reason.

I’m a production editor at an uni press, and I can tell you there’s not a strong correlation between professional/academic level and writing well.

I'm a lawyer. I write 10s of pages of text every day. "Reading through it once yourself" is obviously an imperfect solution. See, e.g., Poisson statistics. It's also slow and I bill in 6-minute increments. There is significant value in a grammar tool that protects confidentiality and is more effective than my wetware.