Label Studio is an open-source (Apache 2.0) data labeling and AI evaluation platform designed for AI/ML practitioners and data science teams. It supports multi-type annotation across computer vision, NLP, audio, time series, and multi-modal data. Label Studio is self-hostable via Docker, pip, Homebrew, or Git, and exposes a programmable interface through a REST API, Python SDK, and webhooks — enabling tight integration into existing ML pipelines and human-in-the-loop workflows. With 28,400+ GitHub stars and a community of 1M+ practitioners, it is one of the most widely adopted open-source labeling solutions available. A paid Enterprise tier extends the Community Edition with additional capabilities.