Typed a few sentences, it corrected a few errors, then told me I needed to pay for premium to detect any further errors.

Premium might be worth it for some people, but for me it's not that serious. I can live with the occasional grammar mistake.

It works better than Grammarly, integrates better with writting web apps such as overleaf or google docs, is cheaper and is open source!

So much better than the alternatives, that I will not give the respect of naming. Instant, never wrong.

LOVE.

Очень крутая штука, так и сам потихоньку учишься писать без ошибок) разрабам мой респект, особенно я набираю очень быстро текст но пока с грамматикой не очень.

Разрабы молотки могут ребята

Un très bon outil, complet et le plus souvent pertinent.
J'utilise quotidiennement depuis 2 ans, en Français et en Anglais.