But the raw model weights were only half the story. The community has long suspected that the source code —the actual training loop, the attention optimization, and the inference server—held secrets that competitors haven't reverse-engineered. After reviewing the Falcon 40 source code exclusive build (version falcon-40b-ee-v3 ), we found three distinct components that separate this model from the LLM herd. 1. The "FlashAttention-2" Custom Fork While standard Falcon implementations use FlashAttention, the source code reveals a proprietary fork called FalconFlash . Unlike standard attention mechanisms that run a unified kernel, FalconFlash dynamically segments sequence lengths.
TII is reportedly preparing a "Source Available Plus" license for Falcon 180 that releases the custom Flash kernels to the public, keeping only the orchestration layer proprietary. If you are a solo developer or a hacker, the public Falcon 40 weights and the open-source community implementation are sufficient. You will run the model, you will fine-tune it, and it will work well. falcon 40 source code exclusive
Unlike standard checkpointing which saves weights every N steps, CriticalCheckpoint snapshots the gradient accumulation state and the random number generator (RNG) state of every node. In exclusive tests, this allowed the TII team to resume training from a node failure in under 90 seconds—a feature not even NVIDIA’s NeMo offers out of the box. This is the controversy hidden within the source code. The public-facing Falcon 40 license is the TII Falcon License 1.0, which is broadly permissive for commercial use. However, the exclusive source code includes comments and preprocessor directives that hint at a dual-licensing model for enterprise support. But the raw model weights were only half the story
But if you are an MLE at a unicorn startup building a production RAG pipeline, the —particularly the FalconFlash attention and the FastFalconTokenizer —is worth the enterprise subscription. The 2x speed boost and the ability to handle 8k context windows natively pay for the license in GPU hours saved within the first month. TII is reportedly preparing a "Source Available Plus"
Specifically, the file tii_legal.h contains the following commented block:
TII has played a clever game. They gave the world a lion, but kept the training manual exclusive. Whether that makes them heroes or villains depends on whether you have the budget to read the fine print. Have you accessed the Falcon 40 exclusive source code? Disagree with our analysis? Reach out to our secure tip line at tips@aiinsider.com. We will update this article as new information breaks.
argue that TII’s move to keep the top-tier kernels exclusive is fair. "Training Falcon 40 cost an estimated $5 million in compute," wrote Reddit user u/LLM_Plumber. "They gave us the weights. Let them make money on the code optimizations."