Ask HN: Niche AI tools you actually find useful?

If you look at ProductHunt and other places like that you’ll just see a sewer pipe full of crappy AI products. But there are surely some out there in different areas that have a nice UI and provide a lot of value. Do you have any that you’ve found? (I’m specifically curious about a language learning tool for complete beginners but wondering about other niches as well)

[dead]