This is great.

If you add a PWA install thing and offline mode that would be interesting to me. Most of my podcast time is on walks. App is useful too for the same reason.

The memorize function<->bookmark relation was not obvious to me, making that clearer would be great. I really like the idea of having a sentence, though, that you can test your understanding of instead of just a word.

The Pimsleur mode is really great idea and I love that it's there but the TTS is atrocious. I'm pretty tolerant, but even I would have a hard time listening to that on an hour-long walk, for example.