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.

Rosetta Stone is known for its signature immersion methodology, which teaches language entirely without translation by relying on picture and word association. This approach encourages learners to develop intuition and "think" in the target language from day one. The program is a highly structured, comprehensive course with a polished interface and a proprietary speech-recognition engine ("TruAccent") for pronunciation feedback. However, the complete lack of explicit grammar explanations and reliance on repetitive matching exercises can be slow and frustrating for learners trying to grasp complex or abstract concepts, making its method effective for some but not all.