trainchinese is an Android app that offers a free Chinese-Spanish dictionary with over 50,000 words and thousands of vocabulary lists, including those based on HSK levels. The words include pinyin, audio, animations for character writing, and many examples. The dictionary is completely free to use.

The app provides a customized flashcard system for personalized vocabulary selection and learning. To use the memorization system, users need to register with trainchinese. Registered users can use it for free as long as they don't exceed a defined weekly quota of words.

The dictionary not only contains words but also thousands of phrases with examples to help users learn how to use them. The search is extremely fast, and users can search using Spanish, pinyin, Chinese characters, or by selecting words from lists or other results. Regardless of whether users are studying simplified Chinese (China mainland and Singapore) or traditional Chinese (Hong Kong and Taiwan), the app includes both. Users can easily switch between the types of Chinese or choose both for dictionary searches or while learning vocabulary.