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Harnesses & SDKs

Frameworks and SDKs for building agents: the Claude Agent SDK, OpenAI Agents SDK, LangGraph, CrewAI and many more. Each page lists languages, packages, MCP and A2A support and how it orchestrates agents, with a link to the page every fact came from.

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Showing 73–96 of 117

NameLanguageStarsDownloads / month (approx.)MCPA2AMulti-agent
Microsoft Agent Framework

Open framework for building and hosting production-grade AI agents and multi-agent workflows in .NET and Python.

Python, C#, Go14.3K~204KNot statedNot statedYes
Foundry

Python framework for agents that discover MCP tools by themselves, with optional memory, guardrails, cache and tracing.

Python892~6.4KBuilt inNot stated—
cayu

Python runtime and framework for long-running agents, with durable sessions, approvals, spend caps and multi-agent collaboration.

Python927~6.4KNot statedNot statedYes
caspian-sdk

Python and TypeScript SDK that lets an agent message people on email, Slack, Discord, Telegram and other channels through one handler.

Python, TypeScript973~244Not statedNot stated—
underthesea

Python toolkit for Vietnamese NLP with a multi-provider agent module that calls LLM APIs using only the standard library.

Python1.8K~36.8KNot statedNot stated—
any-agent

Python interface for running and evaluating agents from several frameworks, with OpenTelemetry traces; now in soft deprecation.

Python1.3K~2.7KBuilt inBuilt inYes
Microsoft Teams SDK

SDK for building Microsoft Teams apps and AI agents in TypeScript, C# and Python, with a CLI that scaffolds new agents.

TypeScript, C#, Python731~2.1MNot statedNot stated—
AgileRL

Library for LLM post-training (SFT, DPO, GRPO and agentic RL) and classic RL, with evolutionary hyperparameter optimization.

Python959~3KNot statedNot statedYes
judge0

Open-source online code execution system that runs submitted code in a sandbox behind an HTTP JSON API.

Python4.5K~746Not statedNot stated—
VeADK

Python SDK for building agents on Volcengine AgentKit, with a bundled Web UI, Studio deployment and short- and long-term memory.

Python347~4.7KNot statedNot statedYes
RAGEN

Reinforcement learning framework for training reasoning LLM agents over multi-turn episodes with the StarPO algorithm.

Python2.8K—Not statedNot stated—
reef

Open-source infrastructure for continually self-improving agents that serves requests, learns from feedback and versions updates.

Python7.7K~334Not statedNot stated—
ir-sim

YAML-driven Python robot simulator for navigation, control and learning research, with collision detection and a Matplotlib renderer.

Python1.2K~1.7KNot statedNot stated—
MS-Agent

Lightweight Python agent framework for long-running tasks, with skills, sub-agents, A2A and ACP servers, and CLI, TUI and web front ends.

Python4.4K~459Not statedBuilt inYes
activegraph

Event-sourced Python graph runtime where agent behaviors react to a shared graph, with an audit trail and fork-and-diff replay.

Python707~2.6KNot statedNot stated—
NVIDIA NeMo Agent Toolkit

Open-source NVIDIA library that connects existing agents to tools and data, with profiling and LangSmith tracing; deprecated, EOL end of 2026.

Python2.7K~128.8KNot statedNot stated—
CGraph

Cross-platform C++ DAG framework with a Python version, for running task graphs with no third-party dependencies.

c++, Python2.3K~506Not statedNot stated—
agent-lightning

Reinforcement-learning trainer of about 3,500 lines that trains models behind agents run in their own harnesses, locally or as Kubernetes jobs.

Python18.8K—Not statedNot stated—
forge

Reliability layer for tool calling with self-hosted LLMs, offered as a proxy, a workflow runner and middleware.

Python2.3K~394Not statedNot stated—
heurist-agent-framework

Multi-interface agent framework with tools, memory and MCP, serving agents through Telegram, Discord, Twitter, Farcaster and a REST API.

Python826—Built inNot stated—
OpenJudge

Open-source Python evaluation framework with ready-made and custom graders for scoring AI agent quality and producing reward signals.

Python888~990Not statedNot stated—
all-agentic-architectures

Python library of 35 agentic AI architectures with one run() interface, built on LangGraph and multiple LLM providers.

Python4.6K—Not statedNot stated—
AgentLab

Framework for developing, evaluating and benchmarking web agents on BrowserGym benchmarks, with parallel runs through Ray.

Python657~1.2KNot statedNot stated—
agentUniverse

Python multi-agent framework with PEER and DOE collaboration patterns and configurable LLM vendors such as Qwen, DeepSeek and OpenAI.

Python2.4K~296Not statedNot statedYes

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