Anki is a powerful, open-source flashcard program renowned for its effective spaced repetition system (SRS). It isn't a language course itself, but a highly effective tool for memorizing vocabulary, phrases, or grammar rules that you input yourself or download from shared user-created decks. Its high degree of customization allows for rich cards with audio, images, and cloze deletions. While its interface can be unintuitive for new users, its effectiveness for long-term retention is largely considered unparalleled for dedicated learners.

Speechling is a non-profit platform singularly focused on improving spoken fluency and pronunciation. The method is simple yet effective: you listen to a sentence from a native speaker, record yourself saying it, and submit your recording for feedback from a human coach. This targeted approach provides personalized corrections that automated speech recognition cannot offer. It is not a comprehensive course for learning a language from scratch, but rather an invaluable tool for learners who have a basic foundation and want to refine their accent and conversational confidence.