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Frameworks & Tools
Outlines
A library that forces model output to match a required structure, such as a fixed data format.
Definition
Outlines is an open-source library that makes language model output conform to a specified structure. As the model writes, it blocks any next word that would break the target format, using pattern-matching rules to enforce data formats like JSON, a fixed list of allowed choices, or other defined templates. This yields output a program can read directly, without retries or cleanup, and it works with serving backends like vLLM and llama.cpp.