Rule-based coach, not an AI model. The core meaning (a listed synonym) earns 0.8 and a key detail earns 0.2, using fixed word lists, so the percentage shows how much of this rubric you hit, not your real understanding. Voice: your recording is sent to a speech-to-text service (Whisper on Groq's free tier) and is not stored by this page; if that is unavailable it falls back to your browser's own speech recognition, which may send audio to your browser's vendor (for example Google in Chrome). Needs a microphone and internet. Typing works in any browser.