Label Studio

Label Studio is HumanSignal's popular open-source data labeling platform for text, image, audio, video, and time series, free to self-host with managed cloud and enterprise tiers.

Label Studio is an open-source, multi-type data labeling tool used by a very large community of AI practitioners to create and refine training data. It handles many data modalities, including text, images, audio, video, and time series, and offers a configurable labeling interface plus a REST API exposing projects, tasks, annotations, predictions, storage, webhooks, and review workflows. Teams use it both to label raw data and to improve existing datasets, and increasingly to prepare data for fine-tuning LLMs and evaluating model outputs. The Community Edition is fully open source and free to self-host with all core labeling features, which has made it a default choice for data-centric ML teams. HumanSignal, the company behind it, also offers a managed Starter Cloud plan and an Enterprise edition that adds role-based access control, SSO, SOC 2 compliance, advanced analytics, workspaces, quality-assurance workflows, reviewer assignments, and SLAs. This tiering lets small teams start free and scale into governed, collaborative labeling operations.