Alternatives to Pydantic AI

AutoGen is Microsoft's open-source framework for building conversational and event-driven multi-agent AI apps in Python and .NET.

Microsoft's open-source, code-first Python framework for building stateful, data-intensive conversational AI agents.

Open-source multi-agent framework that assigns PM, architect, engineer and QA roles to GPTs for structured software tasks

A free, MIT-licensed Python framework from OpenAI for building multi-agent workflows with handoffs, guardrails, and tracing.

Open-source React framework for agent chat, generative UI, and shared state on any AG-UI backend.

Microsoft Agent Framework is an open-source SDK for building agentic AI with workflows, checkpoints, and the GA Agent Harness runtime.

Mastra is an open-source TypeScript agent framework for durable workflows, memory, and built-in agent observability.

SmolAgents builds code-writing AI agents in Python — a ~1,000-line open-source library where agent actions are executable code.

Eino is an open-source Go LLM framework from ByteDance for building agents, graphs, and RAG pipelines in your existing Go backend.

Rig is an open-source Rust LLM framework for building type-safe AI agents with one unified API across 20+ model providers.

Build agentic AI apps in TypeScript, Go, Python, or Dart with Genkit's open-source AI SDK.

Build production AI agents with open source Python and TypeScript harness SDKs you fully control.

Python agent framework for small language models — local engines, OpenAI-compatible servers, or hosted providers, with tool-call tracing

Mirascope is an open-source Python library that turns LLM calls, tools, and prompt versioning into plain decorated functions.

Open-source TypeScript AI SDK for streaming AI apps and agents across 100+ models with built-in fallbacks

Open-source agentic AI data assistant that writes SQL, runs code in a sandbox, and chats with your databases self-hosted

Open-source Python library that constrains LLM decoding so JSON, regex, and grammar outputs are valid on the first call.

Microsoft's open-source SDK for building AI agents and copilots with plugins, memory, and multi-agent orchestration.

Open-source Python library that constrains LLM output with regex, context-free grammars, and inline control flow.

BAML is a type-safe, Turing-complete language for agentic and LLM code that compiles typed Python and TypeScript SDKs.

Hermes Desktop is a free, open-source desktop GUI for the Hermes Agent — a self-hosted AI agent with a built-in learning loop that turns

Hermes Agent: a self-hosted open-source AI agent with persistent memory that builds reusable skills across 20+ chat platforms.

CowAgent is an open-source AI agent harness that plans tasks, runs tools, and grows long-term memory across sessions.

DeerFlow is an open-source SuperAgent harness that runs deep research, coding, and creation tasks in a persistent Docker sandbox.

Open-source AI agent loop that iterates a task list in Docker Sandboxes and commits the results.

Open-source library of 817 structured cybersecurity skill files your AI coding agent loads on demand, mapped to MITRE ATT&CK and licensed Apache 2.0.

Open-source LLM from UC Berkeley that turns natural language into API calls and tool-using agent actions.

Open-source Rust library for building streaming, parallel LLM pipelines — data indexing, retrieval-augmented generation, and autonomous agents.

Open-source (MIT) MCP testing and full-stack MCP App framework for building ChatGPT Apps and Claude Connectors from one React codebase.

Marvin turns ordinary Python functions, classes, and Pydantic models into LLM-powered AI tasks with decorators like @ai_fn and