Outlines
Constrained text generation using regex and context-free grammars
View on GitHubWhat it solves
Guaranteed-valid structured outputs from local/open-weight models: without post-processing or retry loops.
Overview
Outlines constrains LLM text generation at the sampling level: outputs always conform to a regex, JSON schema, or context-free grammar. Works with local models (transformers, llama.cpp) and several hosted APIs. Fundamentally different from retry-based approaches: the constraint is enforced during generation, not after.
Key facts
- Language
- Python
- License
- Apache 2.0
- Maturity
- Fast-moving
- Maintainer
- dottxt-ai
- Reviewed
- 2026-06-11
Where to start
The structured outputs reference shows the three constraint types in concrete examples.
docs/reference/generation/structured_outputs.mdTechnologies
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