BRAT vs CVAT

brat is a free, open-source tool for structured text annotation, with annotations represented in forms computers can process. It supports text spans, binary relations, n-ary associations, attributes, normalization annotations, and freeform notes. Teams can configure categories, types, and constraints for their tasks, and multiple annotators can work on the same document or collection while seeing one another’s edits nearly as they happen. Normalization can link annotations to external resources, and brat can incorporate output from automatic annotation services available as web services. Its server and client support Unicode across nearly 100 scripts. The tool checks edits against configured constraints and searches documents or collections, including keyword-in-context concordancing. Annotations export in brat stand-off format; visualizations can be saved as SVG, PNG, PDF, or EPS. The free v1.3 release is self-hosted under the MIT License. New server installations assume a UNIX-like environment; Windows users can run brat in a UNIX-like virtual machine. The experimental standalone server is not security-hardened and is not recommended for sensitive data or systems accessible from the internet.

CVAT turns images, video, 3D data and audio into labeled datasets for AI workflows. Its annotation tools include boxes, masks, polygons, keypoints, skeletons and object tracks, with additional listed types such as cuboids, ellipses and tags. Teams can review jobs through validation and acceptance stages and assess quality using ground truth, honeypots and consensus workflows. Storage connections include Amazon S3, Azure Blob Storage, Google Cloud Storage, compatible buckets and self-hosted storage. CVAT names SAM 2, SAM 3, Ultralytics, Hugging Face and custom models as labeling aids. It exports to more than 20 formats, including COCO, YOLO, KITTI, Cityscapes and Pascal VOC, and offers API, SDK and CLI automation. Deployment can be managed in the cloud or self-hosted, including on-premises and air-gapped options. Free plans are available; online paid plans start at $23/user/mo billed annually. CVAT lists security controls but says it does not hold ISO 27001 or SOC 2 certifications.