Clozemaster vs Sotto

Clozemaster is a language-learning service built around fill-in-the-blank sentences in context. Learners answer by selecting a choice or typing the missing word, then review sentences again through spaced practice and word-frequency progress tracking. The service lists 75 languages, thousands of sentences in more than 50 languages, and over 170 language pairings. It runs on the web, Android, and iOS, with personalized review and offline lessons. Some sentences have ChatGPT explanations by default, while others can generate an explanation when requested. Sentence and translation data comes from Tatoeba’s user-curated, CC-BY dataset, which may contain errors. The Free plan costs nothing and allows 30 sentences per day.

Sotto is open-source, self-hosted language-learning software for structured CEFR courses and private practice. Its course covers grammar, reading, listening, speaking, and writing, with advancement tied to demonstrated mastery; separate practice is not gated by course progression. A vocabulary and grammar memory graph uses SM-2 spaced repetition to schedule reviews and help shape adaptive listening. Learners can build classes from articles, papers, YouTube links, or topics, with material leveled to a CEFR course and citations provided. Configurable AI and speech services include OpenAI, Anthropic, Ollama, faster-whisper, and Kokoro; Gemini Live supports spoken translation. The application, database, and files run on the operator’s own stack, and the maker documents an offline setup using the learner’s hardware. Access options include a browser-installable PWA, a desktop launcher for macOS, Windows, and Linux, a terminal client, and workbook PDFs for iPad annotation. Sotto is free to run under AGPL-3.0, but users pay configured AI and speech providers directly. Content sent to cloud providers is subject to those providers’ terms.