p-e-w / heretic

# Heretic: Fully automatic censorship removal for language models 
Heretic is a tool that removes censorship (aka "safety alignment") from
transformer-based language models without expensive post-training.
It combines an advanced implementation of directional ablation, also known
as "abliteration" (Arditi et al. 2024,
Lai 2025 (1,
2)),
with a TPE-based parameter optimizer powered by Optuna.
This approach enables Heretic to work **completely automatically.** Heretic
finds high-quality abliteration parameters by co-minimizing the number of
refusals and the KL divergence from the original model. This results in a
decensored model that retains as much of the original model's intelligence
as possible. Using Heretic does not require an understanding of transformer
internals. In fact, anyone who knows how to run a command-line program
can use Heretic to decensor language models.
Heretic supports most dense models, including many multimodal models,
several different MoE architectures, and even some hybrid models like Qwen3.5.
Pure state-space models and certain other research architectures are not yet
supported out of the box.
Running unsupervised with the default configuration, Heretic can produce
decensored models that rival the quality of abliterations created manually
by human experts:
| Model | Refusals for "harmful" prompts | KL divergence from original model for "harmless" prompts |
| :--- | ---: | ---: |
| google/gemma-3-12b-it (original) | 97/100 | 0 *(by definition)* |
| mlabonne/gemma-3-12b-it-abliterated-v2 | 3/100 | 1.04 |
| huihui-ai/gemma-3-12b-it-abliterated | 3/100 | 0.45 |
| **p-e-w/gemma-3-12b-it-heretic (ours)** | **3/100** | **0.16** |
The Heretic version, generated without any human effort, achieves the same
level of refusal suppression as other abliterations, but at a much lower
KL divergence, indicating less damage to the original model's capabilities.
*(You can reproduce those numbers using Heretic's built-in evaluation functionality,
e.g. `heretic --model google/gemma-3-12b-it --evaluate-model p-e-w/gemma-3-12b-it-heretic`.
Note that the exact values might be platform- and hardware-dependent.
The table above was compiled using PyTorch 2.8 on an RTX 5090.)*
Of course, mathematical metrics and automated benchmarks never tell the whole
story, and are no substitute for human evaluation. Models generated with
Heretic have been well-received by users (links and emphasis added):
> "I was skeptical before, but I just downloaded
> **GPT-OSS 20B Heretic**
> model and holy shit. It gives properly formatted long responses to sensitive topics,
> using the exact uncensored words that you would expect from an uncensored model,
> produces markdown format tables with details and whatnot. Looks like this is
> the best abliterated version of this model so far..."
> *(Link to comment)*
> "**Heretic GPT 20b**
> seems to be the best uncensored model I have tried yet. It doesn't destroy a
> the model's intelligence and it is answering prompts normally