I built a tool that shows you what GPT-2 is “thinking” in real-time as it generates 3D graph of concept activations per token

**What Happened:** A user on Reddit has built a tool called AXON, which visualizes the internal workings of GPT-2 in real-time. The…

By AI Maestro May 19, 2026 1 min read
I built a tool that shows you what GPT-2 is “thinking” in real-time as it generates 3D graph of concept activations per token

**What Happened:**
A user on Reddit has built a tool called AXON, which visualizes the internal workings of GPT-2 in real-time. The tool uses a Sparse Autoencoder (SAE) to decompose the residual stream of each token generated by GPT-2 into human-interpretable features such as “European geography,” “capital cities,” and “French language.” These features are then displayed live on a 3D force graph, where nodes represent these features and edges show which features activate together for a given token. This allows users to observe how different concepts and patterns come together before the model outputs them.

**Why It Matters:**
This tool offers unprecedented insight into how large language models like GPT-2 operate internally. By showing what specific features are being activated at each step of generation, it provides a new way for researchers and developers to understand and validate these models. This level of mechanistic interpretability could be crucial in improving the trust and reliability of AI systems, as well as facilitating more robust debugging and testing processes.

– **Enhanced Understanding:** It allows users to see how different concepts are being considered by the model before a particular word is generated.
– **Interpretability:** By exposing the internal mechanisms, it aids in building better explanations for AI outputs and mitigates some of the concerns around black-box models.
– **Research Tool:** This tool can serve as a valuable resource for researchers exploring interpretability techniques applied to LLMs.

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