transformers.js is a JavaScript library designed to offer advanced machine learning capabilities to web applications. It allows users to run pre-trained Transformers models directly in the browser without server support. The library utilizes ONNX Runtime as the backend, supporting the conversion of PyTorch, TensorFlow, or JAX models into ONNX format. transformers.js is equivalent in functionality to the Hugging Face transformers Python library, providing similar APIs to ease the migration of existing code to the web side.