Marvin
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Inputs: textOutputs: code, text
About Marvin
Marvin is a Python framework for producing structured outputs and building agentic AI workflows. It provides an intuitive API for defining workflows and delegating work to LLMs, including casting, classifying, extracting, and generating structured data from any inputs. Users can create discrete, observable tasks with specialized AI agents and combine them into threads for complex orchestration. Built on top of Pydantic AI, Marvin supports multiple LLM providers and offers a simple interface for both structured data extraction and agent-based control flow.
Key Features
Structured-output utilities: extract, cast, classify, and generate data from unstructured input
Agentic control flow with tasks, agents, and threads for complex workflows
Supports multiple LLM providers via Pydantic AI integration
Simple API: marvin.run() for text or structured output generation
Discrete, observable tasks with assignable specialist AI agents
Open-source Python library available on PyPI
Pros & Cons
Pros
- Intuitive and Pythonic API for both beginners and advanced users
- Open-source with active development on GitHub
- Supports both structured output utilities and agentic workflow orchestration
- Works with any LLM provider supported by Pydantic AI
- Lightweight installation and easy configuration
Cons
- Primarily focused on Python ecosystem, limiting use for other languages
- By default uses OpenAI API (requires key) unless other providers configured
- Relatively newer framework (v3.0) with evolving API and documentation
- May have learning curve for complex agentic workflows
Best For
Extracting structured data (numbers, names, amounts) from unstructured textClassifying customer support tickets into predefined departmentsGenerating lists of structured objects (e.g., prime numbers) from descriptionsBuilding multi-step AI workflows with task delegation and agent coordinationCreating intelligent assistants that follow specific instructions and have access to tools
FAQ
What is Marvin?
Marvin is a Python framework for producing structured outputs and building agentic AI workflows, developed by PrefectHQ.
How do I install Marvin?
Marvin is available on PyPI. Install with 'pip install marvin' or 'uv add marvin'.
What LLM providers does Marvin support?
Marvin uses OpenAI by default but natively supports all Pydantic AI models, allowing multiple providers.
Can Marvin extract structured data from text?
Yes, Marvin provides utilities like marvin.extract, marvin.cast, marvin.classify, and marvin.generate for structured output from unstructured input.
Is Marvin free?
Yes, Marvin is open-source and free to use under the Apache 2.0 license.