And why do you think did duolingos competitor "toucan" not take off? How does nuenki do the job better?

Seriously interested and happy to read more insights.

Disclaimer: i did create an MVP of this exactly. But it was just to try and generate some cash quickly to finance my main project (dumb idea, of course). I did get some signups but never even launched the app (and not planning to). Just curious what your experience is.

Toucan did take off; it's fairly well known, and if their website is anything to go by they have hundreds of thousands of people using it.

It translates on a per-word basis, which means that the translations are often simply wrong due to a lack of context. Nuenki doesn't translate single word "sentences" by default, despite me spending a few days trying to improve the quality, because there just isn't enough context to go off of.

They try to mitigate that by only translating certain words, mostly nouns, which limits how much you can learn from it.

They also only have three difficulty levels, while Nuenki assigns a numerical score to each sentence's difficulty and has much finer grained control.

The flip side of that is that it's free, while Nuenki needs to pay for the cost of translation.

I've got ~20 paid subscribers. People on HN seem to love it, and most of my users are from here, while capital-L language learners are hard to market to. There's a lot of AI slop in language learning, and I'm really not good at marketing!