outlines

Generate structured JSON, regex, and Pydantic outputs from local LLMs with constrained token sampling.

Updated Sep 10, 2026
One-click install
npx skills add https://github.com/loteiron/ZeusAgent --skill outlines-loteiron
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/loteiron/ZeusAgent/tree/main/optional-skills/mlops/inference/outlines
Command: npx skills add https://github.com/loteiron/ZeusAgent --skill outlines-loteiron

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires outlines, transformers, vllm, pydantic, and includes references (resource) components.

What problem does it solve? LLMs often produce malformed JSON or free-form text that breaks downstream parsing. This Skill guarantees structurally valid outputs by constraining token generation at the logit level against JSON schemas, Pydantic models, regex patterns, or literal choices. ## Core Features & Use Cases - Guaranteed Valid Structure: Compile output types into token-level automata so invalid JSON, enums, or regex-mismatched text cannot be generated. - Multiple Backends: Works with Transformers, llama.cpp, vLLM, and OpenAI via outlines.from_transformers, from_llamacpp, from_vllm, and from_openai factories. - Pydantic Integration: Pass a Pydantic model as the output type and validate the returned JSON string with model_validate_json. - Use Case: Extract structured company information (name, founded year, industry, employees) from unstructured text using a local Phi-3 or Llama model, with every field guaranteed to match your schema constraints. ## Quick Start Use the outlines skill to extract a user's name, age, and email from this text into a validated Pydantic model with a local Transformers model.

Frequently Asked Questions about outlines

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I generate structured JSON from a local LLM in Python?▼

Use Outlines to wrap a Transformers, llama.cpp, or vLLM model, then call the model directly with a Pydantic model or JSON schema as the output type. The returned JSON string is guaranteed valid and can be parsed with model_validate_json.

Outlines vs Instructor for structured LLM outputs?▼

Outlines offers zero-overhead constrained generation with full local model support and regex constraints, while Instructor focuses on API models with automatic retrying. Choose Outlines for local inference speed and grammar-level control.

Does Outlines work with vLLM for high-throughput serving?▼

Yes, Outlines supports vLLM via outlines.from_vllm, including tensor parallelism across multiple GPUs and AWQ/GPTQ quantization. vLLM delivers the highest throughput for batch structured generation in production.

How do I use Outlines v1 after the pre-1.0 API was removed?▼

In Outlines v1, create a model with outlines.from_transformers, from_vllm, from_llamacpp, or from_openai, then call the model directly with your prompt and output type. The old outlines.generate.json and outlines.models.transformers helpers no longer exist.

Can Outlines constrain generation to a regex pattern?▼

Yes, pass a regex string as the output type and Outlines compiles it into a token-level automaton that filters invalid tokens during generation. The output is guaranteed to match the pattern, such as a phone number format.

What are the limitations of Outlines with OpenAI models?▼

OpenAI support is limited to server-side constrained JSON output and lacks the FSM optimization available with local backends. Advanced features like regex constraints and token-level filtering do not apply to API-based models.