huggingface · qgallouedec · Nov 24, 2025 · Nov 5, 2025 · Nov 6, 2025 · Nov 10, 2025
diff --git a/docs/source/_toctree.yml b/docs/source/_toctree.yml
@@ -58,8 +58,6 @@
   - sections: # Sorted alphabetically
     - local: dpo_trainer
       title: DPO
-    - local: online_dpo_trainer
-      title: Online DPO
     - local: grpo_trainer
       title: GRPO
     - local: kto_trainer
@@ -111,6 +109,8 @@
     title: MiniLLM
   - local: nash_md_trainer
     title: Nash-MD
+  - local: online_dpo_trainer
+    title: Online DPO
   - local: orpo_trainer
     title: ORPO
   - local: papo_trainer

diff --git a/docs/source/dataset_formats.md b/docs/source/dataset_formats.md
@@ -390,14 +390,14 @@ Choosing the right dataset type depends on the task you are working on and the s
 | [`DPOTrainer`] | [Preference (explicit prompt recommended)](#preference) |
 | [`GRPOTrainer`] | [Prompt-only](#prompt-only) |
 | [`KTOTrainer`] | [Unpaired preference](#unpaired-preference) or [Preference (explicit prompt recommended)](#preference) |
-| [`OnlineDPOTrainer`] | [Prompt-only](#prompt-only) |
 | [`RewardTrainer`] | [Preference (implicit prompt recommended)](#preference) |
 | [`RLOOTrainer`] | [Prompt-only](#prompt-only) |
 | [`SFTTrainer`] | [Language modeling](#language-modeling) or [Prompt-completion](#prompt-completion) |
 | [`experimental.bco.BCOTrainer`] | [Unpaired preference](#unpaired-preference) or [Preference (explicit prompt recommended)](#preference) |
 | [`experimental.cpo.CPOTrainer`] | [Preference (explicit prompt recommended)](#preference) |
 | [`experimental.gkd.GKDTrainer`] | [Prompt-completion](#prompt-completion) |
 | [`experimental.nash_md.NashMDTrainer`] | [Prompt-only](#prompt-only) |
+| [`experimental.online_dpo.OnlineDPOTrainer`] | [Prompt-only](#prompt-only) |
 | [`experimental.orpo.ORPOTrainer`] | [Preference (explicit prompt recommended)](#preference) |
 | [`experimental.ppo.PPOTrainer`] | Tokenized language modeling |
 | [`experimental.prm.PRMTrainer`] | [Stepwise supervision](#stepwise-supervision) |

diff --git a/docs/source/example_overview.md b/docs/source/example_overview.md
@@ -53,8 +53,8 @@ Scripts are maintained in the [`trl/scripts`](https://github.com/huggingface/trl
 | [`examples/scripts/kto.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/kto.py) | This script shows how to use the [`KTOTrainer`] to fine-tune a model. |
 | [`examples/scripts/mpo_vlm.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/mpo_vlm.py) | This script shows how to use MPO via the [`DPOTrainer`] to align a model based on preferences using the [HuggingFaceH4/rlaif-v_formatted](https://huggingface.co/datasets/HuggingFaceH4/rlaif-v_formatted) dataset and a set of loss weights with weights. |
 | [`examples/scripts/nash_md.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/nash_md.py) | This script shows how to use the [`experimental.nash_md.NashMDTrainer`] to fine-tune a model. |
-| [`examples/scripts/online_dpo.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/online_dpo.py) | This script shows how to use the [`OnlineDPOTrainer`] to fine-tune a model. |
-| [`examples/scripts/online_dpo_vlm.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/online_dpo_vlm.py) | This script shows how to use the [`OnlineDPOTrainer`] to fine-tune a a Vision Language Model. |
+| [`examples/scripts/online_dpo.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/online_dpo.py) | This script shows how to use the [`experimental.online_dpo.OnlineDPOTrainer`] to fine-tune a model. |
+| [`examples/scripts/online_dpo_vlm.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/online_dpo_vlm.py) | This script shows how to use the [`experimental.online_dpo.OnlineDPOTrainer`] to fine-tune a a Vision Language Model. |
 | [`examples/scripts/openenv/browsergym.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/openenv/browsergym.py) | Simple script to run GRPO training via the [`GRPOTrainer`] with OpenEnv's BrowserGym environment and vLLM |
 | [`examples/scripts/openenv/catch.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/openenv/catch.py) | Simple script to run GRPO training via the [`GRPOTrainer`] with OpenEnv's Catch environment (OpenSpiel) and vLLM |
 | [`examples/scripts/openenv/echo.py`](https://github.com/huggingface/trl/blob/main/examples/scripts/openenv/echo.py) | Simple script to run GRPO training via the [`GRPOTrainer`] with OpenEnv's Echo environment and vLLM. |

diff --git a/docs/source/index.md b/docs/source/index.md
@@ -24,8 +24,8 @@ Below is the current list of TRL trainers, organized by method type (⚡️ = vL
 
 - [`GRPOTrainer`] ⚡️
 - [`RLOOTrainer`] ⚡️
-- [`OnlineDPOTrainer`] ⚡️
 - [`experimental.nash_md.NashMDTrainer`] 🧪 ⚡️
+- [`experimental.online_dpo.OnlineDPOTrainer`] 🧪 ⚡️
 - [`experimental.ppo.PPOTrainer`] 🧪
 - [`experimental.xpo.XPOTrainer`] 🧪 ⚡️
 

diff --git a/docs/source/online_dpo_trainer.md b/docs/source/online_dpo_trainer.md
@@ -28,8 +28,8 @@ Below is the script to train the model:
 ```python
 # train_online_dpo.py
 from datasets import load_dataset
-from trl import OnlineDPOConfig, OnlineDPOTrainer
 from trl.experimental.judges import PairRMJudge
+from trl.experimental.online_dpo import OnlineDPOConfig, OnlineDPOTrainer
 from transformers import AutoModelForCausalLM, AutoTokenizer
 
 model = AutoModelForCausalLM.from_pretrained("Qwen/Qwen2-0.5B-Instruct")
@@ -66,7 +66,7 @@ The best programming language depends on your specific needs and priorities. Som
 
 ## Expected dataset type
 
-Online DPO only requires a [prompt-only dataset](dataset_formats#prompt-only) (unlike offline DPO, that expects [preference dataset](dataset_formats#preference)). The [`OnlineDPOTrainer`] supports both [conversational](dataset_formats#conversational) and [standard](dataset_formats#standard) dataset formats. When provided with a conversational dataset, the trainer will automatically apply the chat template to the dataset.
+Online DPO only requires a [prompt-only dataset](dataset_formats#prompt-only) (unlike offline DPO, that expects [preference dataset](dataset_formats#preference)). The [`experimental.online_dpo.OnlineDPOTrainer`] supports both [conversational](dataset_formats#conversational) and [standard](dataset_formats#standard) dataset formats. When provided with a conversational dataset, the trainer will automatically apply the chat template to the dataset.
 
 ## Usage tips
 
@@ -93,7 +93,7 @@ Instead of a judge, you can chose to use a reward model -- see [Reward Bench](ht
 
 ### Encourage EOS token generation
 
-When using a reward model, we may want the model to generate completions within a given length. During training, the model will generate completions up to the maximum length specified in the `max_new_tokens` argument of [`OnlineDPOConfig`]. If you want to penalize the model for not generating an EOS token before reaching the maximum length, you can use the `missing_eos_penalty` argument of [`OnlineDPOConfig`]:
+When using a reward model, we may want the model to generate completions within a given length. During training, the model will generate completions up to the maximum length specified in the `max_new_tokens` argument of [`experimental.online_dpo.OnlineDPOConfig`]. If you want to penalize the model for not generating an EOS token before reaching the maximum length, you can use the `missing_eos_penalty` argument of [`experimental.online_dpo.OnlineDPOConfig`]:
 
 ```python
 training_args = OnlineDPOConfig(..., max_new_tokens=128, missing_eos_penalty=1.0)
@@ -147,7 +147,7 @@ While training and evaluating, we record the following reward metrics. Here is a
 * `logps/chosen`: The mean log probabilities of the chosen completions.
 * `logps/rejected`: The mean log probabilities of the rejected completions.
 * `val/contain_eos_token`: The fraction of completions which contain an EOS token.
-* `beta`: The parameter that controls the weight of the loss term representing the deviation from the reference model. Typically fixed, but can be made dynamic by passing a list to [`OnlineDPOConfig`].
+* `beta`: The parameter that controls the weight of the loss term representing the deviation from the reference model. Typically fixed, but can be made dynamic by passing a list to [`experimental.online_dpo.OnlineDPOConfig`].
 
 ## Benchmark experiments
 
@@ -261,11 +261,11 @@ The online DPO checkpoint gets increasingly more win rate as we scale up the mod
 
 ## OnlineDPOTrainer
 
-[[autodoc]] OnlineDPOTrainer
+[[autodoc]] experimental.online_dpo.OnlineDPOTrainer
     - train
     - save_model
     - push_to_hub
 
 ## OnlineDPOConfig
 
-[[autodoc]] OnlineDPOConfig
+[[autodoc]] experimental.online_dpo.OnlineDPOConfig
diff --git a/docs/source/reducing_memory_usage.md b/docs/source/reducing_memory_usage.md
@@ -265,7 +265,7 @@ training_args = GRPOConfig(..., ds3_gather_for_generation=False)
 <hfoption id="Online DPO">
 
 ```python
-from trl import OnlineDPOConfig
+from trl.experimental.online_dpo import OnlineDPOConfig
 
 training_args = OnlineDPOConfig(..., ds3_gather_for_generation=False)
 ```

diff --git a/docs/source/speeding_up_training.md b/docs/source/speeding_up_training.md
@@ -20,7 +20,7 @@ pip install trl[vllm]
 Then, enable it by passing `use_vllm=True` in the training arguments.
 
 ```python
-from trl import OnlineDPOConfig
+from trl.experimental.online_dpo import OnlineDPOConfig
 
 training_args = OnlineDPOConfig(..., use_vllm=True)
 ```

diff --git a/docs/source/vllm_integration.md b/docs/source/vllm_integration.md
@@ -9,9 +9,9 @@ This document will guide you through the process of using vLLM with TRL for fast
 > The following trainers currently support generation with vLLM:
 >
 > - [`GRPOTrainer`]
-> - [`OnlineDPOTrainer`]
 > - [`RLOOTrainer`]
 > - [`experimental.nash_md.NashMDTrainer`]
+> - [`experimental.online_dpo.OnlineDPOTrainer`]
 > - [`experimental.xpo.XPOTrainer`]
 
 ## 🚀 How can I use vLLM with TRL to speed up training?
@@ -65,7 +65,7 @@ trainer.train()
 
 ```python
 from datasets import load_dataset
-from trl import OnlineDPOTrainer, OnlineDPOConfig
+from trl.experimental.online_dpo import OnlineDPOConfig, OnlineDPOTrainer
 from trl.rewards import accuracy_reward
 
 dataset = load_dataset("trl-lib/DeepMath-103K", split="train")
@@ -316,7 +316,7 @@ training_args = GRPOConfig(
 <hfoption id="OnlineDPO">
 
 ```python
-from trl import OnlineDPOConfig
+from trl.experimental.online_dpo import OnlineDPOConfig
 
 training_args = OnlineDPOConfig(
     ...,
@@ -391,7 +391,7 @@ training_args = GRPOConfig(
 <hfoption id="OnlineDPO">
 
 ```python
-from trl import OnlineDPOConfig
+from trl.experimental.online_dpo import OnlineDPOConfig
 
 training_args = OnlineDPOConfig(
     ...,

diff --git a/examples/scripts/online_dpo.py b/examples/scripts/online_dpo.py
@@ -58,15 +58,14 @@
 from trl import (
     LogCompletionsCallback,
     ModelConfig,
-    OnlineDPOConfig,
-    OnlineDPOTrainer,
     ScriptArguments,
     TrlParser,
     get_kbit_device_map,
     get_peft_config,
     get_quantization_config,
 )
 from trl.experimental.judges import HfPairwiseJudge, OpenAIPairwiseJudge, PairRMJudge
+from trl.experimental.online_dpo import OnlineDPOConfig, OnlineDPOTrainer
 
 
 # Enable logging in a Hugging Face Space

diff --git a/examples/scripts/online_dpo_vlm.py b/examples/scripts/online_dpo_vlm.py
@@ -92,14 +92,13 @@
 from trl import (
     LogCompletionsCallback,
     ModelConfig,
-    OnlineDPOConfig,
-    OnlineDPOTrainer,
     ScriptArguments,
     TrlParser,
     get_kbit_device_map,
     get_peft_config,
     get_quantization_config,
 )
+from trl.experimental.online_dpo import OnlineDPOConfig, OnlineDPOTrainer
 from trl.rewards import accuracy_reward, think_format_reward
 
 

diff --git a/tests/test_online_dpo_trainer.py → ...s/experimental/test_online_dpo_trainer.py b/tests/test_online_dpo_trainer.py → ...s/experimental/test_online_dpo_trainer.py
@@ -19,9 +19,9 @@
 from transformers import AutoModelForCausalLM, AutoModelForSequenceClassification, AutoTokenizer
 from transformers.utils import is_peft_available, is_vision_available
 
-from trl import OnlineDPOConfig, OnlineDPOTrainer
+from trl.experimental.online_dpo import OnlineDPOConfig, OnlineDPOTrainer
 
-from .testing_utils import (
+from ..testing_utils import (
     RandomPairwiseJudge,
     TrlTestCase,
     require_llm_blender,

diff --git a/trl/experimental/nash_md/nash_md_config.py b/trl/experimental/nash_md/nash_md_config.py
@@ -14,15 +14,15 @@
 
 from dataclasses import dataclass, field
 
-from ...trainer.online_dpo_config import OnlineDPOConfig
+from ..online_dpo import OnlineDPOConfig
 
 
 @dataclass
 class NashMDConfig(OnlineDPOConfig):
     r"""
     Configuration class for the [`experimental.nash_md.NashMDTrainer`].
 
-    Subclass of [`OnlineDPOConfig`] we can use all its arguments and add the following:
+    Subclass of [`experimental.online_dpo.OnlineDPOConfig`] we can use all its arguments and add the following:
 
     Parameters:
         mixture_coef (`float` or `list[float]`, *optional*, defaults to `0.5`):

diff --git a/trl/experimental/nash_md/nash_md_trainer.py b/trl/experimental/nash_md/nash_md_trainer.py
@@ -37,8 +37,8 @@
 from ...models.modeling_base import GeometricMixtureWrapper
 from ...models.utils import unwrap_model_for_generation
 from ...trainer.judges import BasePairwiseJudge
-from ...trainer.online_dpo_trainer import OnlineDPOTrainer
 from ...trainer.utils import SIMPLE_CHAT_TEMPLATE, empty_cache, get_reward, selective_log_softmax, truncate_right
+from ..online_dpo import OnlineDPOTrainer
 from .nash_md_config import NashMDConfig
 
 
@@ -50,7 +50,7 @@ class NashMDTrainer(OnlineDPOTrainer):
     """
     Trainer for the Nash-MD method.
 
-    It is implemented as a subclass of [`OnlineDPOTrainer`].
+    It is implemented as a subclass of [`experimental.online_dpo.OnlineDPOTrainer`].
 
     Args:
         model ([`~transformers.PreTrainedModel`]):

diff --git a/trl/experimental/online_dpo/__init__.py b/trl/experimental/online_dpo/__init__.py
@@ -0,0 +1,19 @@
+# Copyright 2020-2025 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .online_dpo_config import OnlineDPOConfig
+from .online_dpo_trainer import OnlineDPOTrainer
+
+
+__all__ = ["OnlineDPOConfig", "OnlineDPOTrainer"]