Here's a list of all the apps (built by them!) mentioned in comments:

- LangTurbo (by @sebnun) - langturbo.com : Learn through podcasts with transcriptions and contextual word definitions

- Nuenki (by @Alex-Programs) - nuenki.app : Browser extension that translates appropriate-difficulty sentences across websites, with hover-for-definitions feature

- Manabi Reader (by @wahnfrieden) - reader.manabi.io : Japanese-focused integrated reader with SRS and Anki integration

- (by @muth02446) - Spanish: appicenter.net/Apps/VocabES/ - English: appicenter.net/Apps/VocabEN/ : Uses spaced repetition and audio for basic vocabulary learning

- Vocabuo (by @kebsup) - vocabuo.com : Combines SRS flashcards with ebook/YouTube/website reader, using AI for content generation

- LingoStories (by @laurentlb) - github.com/laurentlb/lingostories/ : Open-source language learning tool

- Turkish Learning Tool (by @learning-tr) : Browser extension for colloquial translations with audio and pronunciation features

- Language Reactor (by @davidzweig) : Planning to open-source soon, looking for contributors

Note: above list is summarized by Claude 3.5 Sonnet.