SpeechBrain is an open-source toolkit designed to provide state-of-the-art technologies for a wide range of speech and audio processing tasks. It supports techniques for speech recognition, enhancement, separation, text-to-speech, speaker recognition, speech-to-speech translation, and spoken language understanding. The toolkit further encapsulates various audio technologies, including vocoding, audio augmentation, feature extraction, sound event detection, beamforming, and other multi-microphone signal processing capabilities. SpeechBrain also provides tools for the training of Language Models, from basic n-gram LMs to modern Large Language Models, which are seamlessly integrated into speech processing pipelines. Developed to facilitate the research and development of Conversational AI technologies, this toolkit comes with pre-built recipes for popular datasets, extensive documentation, tutorials, and user-friendly interfaces for pre-trained models. It is engineered for adaptability, flexibility, and transparency in order to cater to the needs of various users. The system is designed to be easy to install, use, and customize.