Instructor

Structured outputs from LLMs using Pydantic — patches OpenAI/Anthropic/Cohere/etc. clients to return validated typed objects with retries.

llm-gateway-frameworksNew to PyRadar
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⭐ 13,078 stars⬇ 3.0M downloads/wkFirst release: Jul 2023Last release: Apr 2026
Async Support: YesPlugin Extensions: HighSpeed: FastDoc Quality: HighLearning Curve: Easy

Pros

  • Type-safe LLM outputs via Pydantic response_model — validated objects, not strings
  • Automatic retries with parsing errors fed back to the model
  • Multi-provider — patches OpenAI, Anthropic, Cohere, Gemini, Mistral, and more

Cons

  • Works by patching client libraries, which can feel implicit and surprising
  • response_model feature coverage and reliability vary by underlying provider
  • Adds parsing/validation latency compared to raw streaming

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