Duolingo vs Sotto

Duolingo offers learning in languages, chess and math through short lessons that adapt to a learner’s level and pace. Language practice covers reading, writing, listening and speaking, with speech exercises, personalized review, offline lessons and a placement test among the listed tools. Challenges, reminders and game-like features provide ways to structure practice. Duolingo says its teaching methods are research-backed and aimed at real-world communication skills. It lists 40 languages and is available on Android, iOS, macOS and the web. The pricing note includes a free plan and a 14-day trial. Other listed products include the Duolingo English Test, Duolingo for Business, Duolingo for Schools, Super Duolingo and Duolingo Max. The English Test is described as AI-enabled and intended to be taken wherever and whenever users perform best. FAQs and service status information are available. Duolingo was founded in 2011 and is headquartered in Pittsburgh, Pennsylvania.

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.