Magenta.js is a collection of TypeScript libraries that run TensorFlow.js models in the browser for generative music and art tasks. It includes MusicVAE, MelodyRNN, DrumsRNN, PerformanceRNN, and ImprovRNN for music generation, SketchRNN for sketch generation, and arbitrary style transfer for images. All models are pre-trained and run client-side without server infrastructure.