BRAT review
A focused, self-hosted choice for structured NLP and corpus annotation.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
BRAT is an open-source, browser-based tool for structured annotation of text documents. It is designed for researchers and teams working on natural-language processing, corpus development, information extraction, and related workflows. Its annotation model covers text spans, binary relations, events, attributes, and equivalence annotations, while configurable annotation types and constraints support custom schemes. Human review and model-assisted labeling are supported through collaborative annotation and external automatic annotation web services.
The product’s main strength is depth within structured text annotation. Multiple annotators can work through a server-coordinated workflow, compare annotation sets, and search or concordance across documents and collections. BRAT also supports document collection import and export, with output formats including standoff, SVG, PNG, PDF, and EPS. Integrations with external annotation web services, Freebase, Wikipedia, and Open Biomedical Ontologies extend its fit for research datasets and knowledge-oriented projects.
BRAT is self-hosted, so teams install the server locally rather than selecting among hosted subscription tiers. That deployment model can suit organizations that want control over their annotation environment, but it places setup responsibility on the team. The product’s focus is intentionally narrow: it is built around text and structured linguistic or semantic annotation, not a broad set of labeling modalities. Choose BRAT when complex text relationships, customizable annotation schemes, collection-level search, and research workflows matter most. Teams seeking image, audio, or video labeling, or a broader commercial data-labeling platform, should consider a different category fit.
BRAT pros and cons
- Where it wins
- Supports spans, relations, events, attributes, and equivalence annotations
- Enables collaborative editing and comparison across annotation sets
- Connects external annotation services and exports to multiple formats
- Where it doesn't
- Focused on text rather than multimodal labeling
- Self-hosted deployment requires a locally installed server
- Its research-oriented scope may not suit broad labeling programs
BRAT fact sheet, pricing and score →
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
Last updated · How we research and update