Best AI agents for training and fine-tuning agents (2026)
Platforms and open-source libraries for fine-tuning models and training agents with reinforcement learning, so they get better at your specific tasks. We list 9 tools for training and fine-tuning agents below, each with a link-checked page, pricing as the maker states it and alternatives.
Agent Lightning
Microsoft's lightweight trainer that improves existing agents with reinforcement learning through a model proxy, without rewriting the agent's tools or control flow.
NVIDIA TAO Agent Skills
NVIDIA's vision-model post-training toolkit, now packaged as agent skills so Claude Code or Codex can fine-tune, optimize and export vision foundation models from plain-English prompts.
OpenPipe
Reinforcement learning tooling, including the ART library, to train better agents.
Oumi
Open platform for fine-tuning, evaluating and deploying open agentic LLMs and VLMs.
AReaL
Reinforcement learning system for training LLM-based agents.
Prime Intellect
Decentralized compute and open RL environment hub for training agentic models.
RAGEN
Reinforcement learning framework for multi-turn LLM agents.
CoreWeave Forge
One product to run, observe, evaluate and post-train agents (W&B, OpenPipe, sandboxes).
Together AI
AI cloud for running, fine-tuning and serving open models.
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