What problem does it solve?
Outlines solves the problem of unreliable LLM outputs by guaranteeing that generations conform to a target structure such as valid JSON, regex patterns, or Pydantic-defined types—so downstream systems can consume results safely without fragile post-processing.
Core Features & Use Cases
- Structured generation: Produce syntactically valid JSON/XML/code using schemas and grammars instead of best-effort text.
- Type-safe outputs with Pydantic: Define a Pydantic model and generate instances that match required fields and constraints.
- Backend flexibility: Run with local model backends including Transformers, llama.cpp (GGUF), and vLLM, and support constrained decoding to speed up inference.
- Output controls: Constrain token sampling with grammar-based decoding (FSM), enabling strict adherence to schema/regex and reducing validation retries.
Use case examples:
- Extract entities from a news article into a Pydantic model (e.g., people, organizations, locations).
- Classify sentiment while enforcing a fixed label set and returning a typed confidence field.
- Generate production-ready JSON for downstream APIs (e.g., invoice objects, job applications) with constraints like ranges, patterns, and enums.
Quick Start
Ask an AI to extract information from your text into a defined Pydantic schema using outlines structured JSON generation on your chosen local model.