Chemical Substances: Chem-Quiz

Duolingo is an app for independent language learning through short gamified lessons with pronunciation, reading, listening, and writing exercises. In practice, it frequently has issues with audio, progress synchronization, and content loading.

A full-featured German-Russian dictionary with spaced repetition, examples, and AI chat. Working features include search across 160K words, conjugation tables, audio playback, and collections; server stability issues, AI chat errors, and cloud integration problems exist.

HelloChinese is an application for fun, convenient and effective learning of the Chinese language.

An app for step-by-step learning of programming (Python, JavaScript, HTML, CSS, SQL) with interactive lessons, practical projects, and AI assistant support in a mobile code editor, though with significant stability issues and free access limitations.

An app for creating and studying personal vocabularies with game modes (flashcards, crosswords, spelling quizzes), Google Drive synchronization support, and vocabulary export/import functionality.

WordsApp is a game-based app for learning English that uses an intelligent spaced repetition algorithm to memorize vocabulary and grammar through game mechanics, but frequently crashes during audio playback and has stability issues.

Language learning app with word flashcards, numerous exercises, and built-in dictionaries for popular languages. Allows adding words manually or from a browser, practicing with 9 types of exercises, and tracking progress.

A language learning app using spaced repetition and AI-based contextual vocabulary study. Primarily paid; experiences access issues in Russia and frequent audio playback failures.