Chatterbox is a state-of-the-art open-source text-to-speech library by Resemble AI, providing multiple TTS models (Chatterbox, Chatterbox-Multilingual, Chatterbox-Turbo, Chatterbox-Nano) and voice conversion. The architecture is modular: a T3 transformer generates speech tokens from text conditioned on speaker embeddings and optional reference audio; an S3Gen pipeline converts tokens to mel-spectrograms via conditional flow matching (CFM) and then to waveforms via a HiFiGAN vocoder. Voice cloning is achieved through a separate voice encoder (LSTM-based speaker embedding) and S3 tokenizer for prompt conditioning. The library supports 23+ languages with sophisticated multilingual tokenization (Cangjie for Chinese, hiragana for Japanese, diacritics for Hebrew, stress for Russian, Jamo decomposition for Korean). All models include imperceptible neural watermarking via Perth. The codebase is well-structured, with clean separation of concerns, efficient inference (KV caching, CFG, distilled single-step decoder for Turbo/Nano), and pinned dependencies. It is primarily an application library but includes research-grade model implementations.