vllm/docs/contributing/model/registration.md
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Signed-off-by: reidliu41 <reid201711@gmail.com>
Co-authored-by: reidliu41 <reid201711@gmail.com>
2025-05-25 01:40:31 -07:00

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---
title: Registering a Model to vLLM
---
[](){ #new-model-registration }
vLLM relies on a model registry to determine how to run each model.
A list of pre-registered architectures can be found [here][supported-models].
If your model is not on this list, you must register it to vLLM.
This page provides detailed instructions on how to do so.
## Built-in models
To add a model directly to the vLLM library, start by forking our [GitHub repository](https://github.com/vllm-project/vllm) and then [build it from source][build-from-source].
This gives you the ability to modify the codebase and test your model.
After you have implemented your model (see [tutorial][new-model-basic]), put it into the <gh-dir:vllm/model_executor/models> directory.
Then, add your model class to `_VLLM_MODELS` in <gh-file:vllm/model_executor/models/registry.py> so that it is automatically registered upon importing vLLM.
Finally, update our [list of supported models][supported-models] to promote your model!
!!! warning
The list of models in each section should be maintained in alphabetical order.
## Out-of-tree models
You can load an external model using a plugin without modifying the vLLM codebase.
!!! info
[vLLM's Plugin System][plugin-system]
To register the model, use the following code:
```python
from vllm import ModelRegistry
from your_code import YourModelForCausalLM
ModelRegistry.register_model("YourModelForCausalLM", YourModelForCausalLM)
```
If your model imports modules that initialize CUDA, consider lazy-importing it to avoid errors like `RuntimeError: Cannot re-initialize CUDA in forked subprocess`:
```python
from vllm import ModelRegistry
ModelRegistry.register_model(
"YourModelForCausalLM",
"your_code:YourModelForCausalLM"
)
```
!!! warning
If your model is a multimodal model, ensure the model class implements the [SupportsMultiModal][vllm.model_executor.models.interfaces.SupportsMultiModal] interface.
Read more about that [here][supports-multimodal].
!!! note
Although you can directly put these code snippets in your script using `vllm.LLM`, the recommended way is to place these snippets in a vLLM plugin. This ensures compatibility with various vLLM features like distributed inference and the API server.