I actually had several custom tools that heavily automated card creation—I could grab a sentence from a web page, or bulk import highlighted phrases from an ebook. Then I had a UI which allowed me to easily highlight an interesting word, and either cloze it, or add a Wiktionary definition on the back. Then I had an Anki plugin to bulk import the cards. This could all obviously be combined into a single tool, and occasionally someone tries.

For my most heavily automated experiment, I used a tool similar to subs2srs to import sound, bilingual subtitles, and tiny screen captures from 4 episodes of Avatar: The Last Airbender. That was a fascinating experience, and I'm still earwormed with the dialogue of those episodes a decade later, after only a couple of months of Anki reviews. (See elsewhere in this thread for a link.)

Unfortunately, I'm not convinced that there's a good startup market for language-learning tools. Language learning is normally aspirational, much like a gym membership. And customers don't have any serious plans on how to reach their stated goals. (Again, like a gym membership.) Duolingo isn't terrible, but I suspect—based on lots of Anki experiments—that it should be possible to build much more effective tools than Duolingo. I'm just not convinced that anyone but serious ESL students would pay for them. Too many genuinely good tools in this space have sunken quietly, despite a user-friendly UI and a good landing page.

I guess I am of the few that would pay for a good tool aimed at serious learners, but as I could not find any (in language space almost everything is a Duolingo clone), I am building myself.

So far I think I have proved my main hypothesis: it works really well for me. It's not magic, but it saves me many hours of learning.

Whether it could work for someone else, is an entirely different story... but on the other hand, I have no big ambitions.

It can do sentence card creation, ereader imports, and vocab tracking, among other things.

Unfortunately, it seems like Duolingo is terrible.

Spaced repetition cards seem to blow it away.

I recommend this interview with Duolingo's founder Luis von Ahn: https://www.npr.org/2020/05/22/860884062/recaptcha-and-duoli...

Explicitly, by writing explanations of various grammatical phenomena on flashcards. Implicitly, with usage examples that demonstrate how the grammar works.

Flashcards can teach you pronunciation.

Explicitly, by writing explanations of how to produce various sounds on flashcards. Implicitly, with recordings that demonstrate how things are pronounced. (Ok, paper flashcards can't do that, but we're not talking about those, right?)

If I need an explanation I just paste it into ChatGPT and ask for a breakdown.