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*This model was contributed to Hugging Face Transformers on 2026-10-12.*

# Kolibri1

[Kolibri 1](https://huggingface.co/Aleph-Alpha/Kolibri-1) is Aleph Alpha's mixture-of-experts reasoning model with a focus on German and English. Each of its 50 layers routes every token to 6 of 384 experts with sigmoid routing and adds one shared expert. Four sliding-window attention layers alternate with one full-attention layer, and RoPE is applied only in the sliding-window layers.

```python
from transformers import AutoModelForCausalLM, AutoTokenizer

tokenizer = AutoTokenizer.from_pretrained("Aleph-Alpha/Kolibri-1-BF16")
model = AutoModelForCausalLM.from_pretrained("Aleph-Alpha/Kolibri-1-BF16", device_map="auto")

messages = [{"role": "user", "content": "Erkläre kurz, was ein Mixture-of-Experts-Modell ist."}]
inputs = tokenizer.apply_chat_template(
    messages, add_generation_prompt=True, return_tensors="pt", return_dict=True
).to(model.device)
outputs = model.generate(**inputs, max_new_tokens=256)
print(tokenizer.decode(outputs[0, inputs["input_ids"].shape[1] :], skip_special_tokens=True))
```

## Kolibri1Config

[[autodoc]] Kolibri1Config

## Kolibri1Model

[[autodoc]] Kolibri1Model
    - forward

## Kolibri1ForCausalLM

[[autodoc]] Kolibri1ForCausalLM
    - forward