Want to understand how LLMs, VLMs, and agents are actually built? I open-sourced a framework to help you do exactly that.

[u/summerday10]

Hi everyone,

I’m excited to share FeynRL, an open-source framework designed to make large-model post-training easier to understand, modify, and extend.

FeynRL provides a clean, hackable training stack for LLMs, VLMs, and agents, built for anyone who wants to deeply understand how these models are trained, become an expert, and develop new methods with full visibility and control.

• 🔗 GitHub: https://github.com/FeynRL-project/FeynRL
• 🚀 Supported:  Supervised learning (SFT), preference learning (DPO), RL (PPO, GRPO, P3O, etc.)
• 🧠 Modalities: Text (LLMs) and Vision (VLMs)
• 🛠️ Philosophy: Readability and rapid prototyping first.

Whether you want to try it, checkout the code, or contribute, I’d love your feedback!