Extracting structured information from sprawling text documents is a major hurdle for developers and businesses. LangExtract, Google’s open-source Python library built on Gemini models, offers an advanced solution for transforming unstructured data into reliable, structured formats that make information extraction more precise, scalable, and traceable than ever.
Key Features That Set LangExtract Apart
- Source Grounding: Every piece of extracted data is mapped to its specific location within the original text. This not only enhances trust in the extraction process but also provides transparency, allowing users to easily validate results.
- Structured, Consistent Outputs: By allowing developers to define custom schemas and provide example outputs, LangExtract harnesses Gemini’s controlled generation for dependable and repeatable results even with massive datasets.
- Long-Context Optimization: LangExtract can efficiently process documents with millions of tokens. It divides large texts into chunks and performs parallel extraction, ensuring important details aren’t missed, no matter the scale.
- Interactive Visualization: Rapid, self-contained HTML visualizations offer an intuitive way to examine thousands of annotations within their original context, making validation and sharing of results straightforward for teams and stakeholders.
- Model Flexibility: Though designed for Gemini, LangExtract supports a range of cloud and open-source LLMs. This flexibility lets users choose the language model that best suits their project’s needs.
- Domain Adaptability: Without requiring LLM fine-tuning, LangExtract is capable of adapting to a variety of fields, from healthcare and law to finance and literature. A few well-crafted examples are all it takes for the library to generalize its extraction capabilities to new domains.
- World Knowledge Integration: The system doesn’t just extract what’s explicitly in the text—it can supplement outputs with inferred insights, depending on the language model’s knowledge and the specificity of provided prompts.
Getting Started with LangExtract
Installation is effortless, and usage is straightforward. Developers set extraction objectives using clear prompts and a handful of high-quality examples. For example, extracting characters and emotional relationships from Shakespearean plays can be accomplished quickly, with results output in structured formats like JSONL. The library’s interactive HTML visualizations work seamlessly in environments such as Google Colab or can be downloaded for offline review.
Use Cases: From Clinical Text to Radiology
LangExtract’s versatility is evident in specialized domains. In healthcare, it can accurately pinpoint medications, dosages, and their interrelationships from clinical notes—a feature with roots in medical information extraction research.
In radiology, demos like RadExtract on Hugging Face show how free-text reports can be transformed into structured, actionable summaries, supporting improved workflows in clinical settings.
Safety, Reliability, and Best Practices
While LangExtract’s extraction quality is impressive, Google stresses that current demos are for illustration only and not intended for direct clinical decision-making. Extraction accuracy depends on factors such as the choice of language model and the design of prompts—especially when making use of inferred world knowledge.
Empowering Developers to Extract More
LangExtract unlocks new efficiencies for those working with unstructured text. Developers can explore the LangExtract GitHub repository, try example notebooks, and begin extracting structured insights from their own data. By combining traceability, scalability, and domain adaptability, LangExtract sets a new standard for accessible and auditable information extraction across industries.

How LangExtract Is Revolutionizing Information Extraction from Unstructured Text