Carlos App is a "ChatGPT wrapper" that is audio-based (no text interface, you have to speak into your mic), designed to help you gain fluency in a second language, supplemental to other practice.<p>Carlos's grammatical accuracy/fluency varies by language. For major languages, it's pretty good. Pronunciation is good across the board, which means that there is still an audio immersion benefit even for languages that have relatively less representation in the GPT training data. However, for such languages there may be minor grammatical inaccuracies.<p>Pretty early product here, been working on it for about a month & would greatly appreciate feedback.