Best smolagents Alternatives in 2026

OpenAI's official open-source framework for multi-agent workflows. Launched March 2025 as the production successor to Swarm. Provides handoffs, guardrails, tracing, and voice agent support in Python and TypeScript.

PydanticAI is an open-source Python framework for building production-grade AI agents. Created by Samuel Colvin (creator of Pydantic), it brings FastAPI-style type safety, structured outputs, and dependency injection to agent development. Free, MIT-licensed, 16k+ GitHub stars.

Agno is an open-source Python framework for building multi-agent AI systems, rebranded from Phidata in January 2025. Model-agnostic, Apache 2.0, with built-in memory, knowledge bases, and a production-ready AgentOS runtime for deploying agents as services.

OpenHands is an open-source autonomous AI coding agent by All Hands AI. It plans, writes, executes, and debugs code inside a sandboxed environment without requiring manual approval at every step. Free to self-host; cloud tier available.

OpenAI Codex CLI is an open-source terminal agent that reads your codebase, edits files, and runs shell commands with OS-level sandboxing. Released April 2025, rewritten in Rust, free under Apache 2.0.

SWE-Agent is an open-source autonomous software engineering agent from Princeton University that uses a custom Agent-Computer Interface to resolve GitHub issues, fix bugs, and tackle cybersecurity challenges. Free, MIT-licensed, model-agnostic.

Vercel AI SDK is an open-source TypeScript toolkit for building AI-powered applications and agents. It provides a unified API across 20+ model providers, streaming UI hooks for React and Vue, structured output with Zod, and a full agent abstraction layer.

Genkit is Google's open-source AI framework for TypeScript, Go, and Python developers. It provides typed flows, RAG, tool calling, and multi-agent support with a standout local Developer UI for iterating prompts and debugging traces. Free under Apache 2.0.

Letta is the open-source agent framework from UC Berkeley's MemGPT research team. It gives AI agents persistent, self-editable memory using an OS-inspired three-tier architecture. Apache 2.0 with a cloud-hosted API option.

Haystack is deepset's open-source Python framework for building production-ready RAG pipelines and AI agents. Apache 2.0 licensed, it gives developers explicit control over retrieval, context routing, and generation through composable, YAML-serializable pipeline graphs.