It uses OpenAI's realtime API to simulate either a tutoring session (the speaker will revert to English to help you) or a first date or business meeting (the speaker will always speak the target language)
You can see the AI's transcriptions but not your own, limitation of the current OpenAI API but definitely something I can fix.
The prompts are like this: https://gist.github.com/jc4p/d8b9d121425ec191d62602d8720eeed... and the rest of it is a Nextjs app wrapped around the WebRTC connection.
I'm not fully in love with the app so I'd love any feedback or hearing if it works well for you -- It doesn't have a lot of features yet (including saving context) and if you bump into the time limit just open it up in incognito to keep going.