Welcome to verl's documentation! ================================================ verl is a flexible, efficient and production-ready RL training framework designed for large language models (LLMs) post-training. It is an open source implementation of the `HybridFlow `_ paper. verl is flexible and easy to use with: - **Easy extension of diverse RL algorithms**: The hybrid programming model combines the strengths of single-controller and multi-controller paradigms to enable flexible representation and efficient execution of complex Post-Training dataflows. Allowing users to build RL dataflows in a few lines of code. - **Seamless integration of existing LLM infra with modular APIs**: Decouples computation and data dependencies, enabling seamless integration with existing LLM frameworks, such as PyTorch FSDP, Megatron-LM, vLLM and SGLang. Moreover, users can easily extend to other LLM training and inference frameworks. - **Flexible device mapping and parallelism**: Supports various placement of models onto different sets of GPUs for efficient resource utilization and scalability across different cluster sizes. - Ready integration with popular HuggingFace models verl is fast with: - **State-of-the-art throughput**: By seamlessly integrating existing SOTA LLM training and inference frameworks, verl achieves high generation and training throughput. - **Efficient actor model resharding with 3D-HybridEngine**: Eliminates memory redundancy and significantly reduces communication overhead during transitions between training and generation phases. -------------------------------------------- .. _Contents: .. toctree:: :maxdepth: 2 :caption: Quickstart start/install start/quickstart start/multinode start/ray_debug_tutorial start/more_resources start/agentic_rl .. toctree:: :maxdepth: 2 :caption: Programming guide extend_guide hybrid_flow single_controller .. toctree:: :maxdepth: 1 :caption: Data Preparation preparation/prepare_data preparation/reward_function .. toctree:: :maxdepth: 2 :caption: Configurations examples/config .. toctree:: :maxdepth: 1 :caption: PPO Example examples/ppo_code_architecture examples/gsm8k_example examples/megatron_fsdp_example examples/multi_modal_example examples/skypilot_examples .. toctree:: :maxdepth: 1 :caption: Algorithms algo/ppo.md algo/grpo.md algo/dapo.md algo/spin.md algo/sppo.md algo/entropy.md algo/opo.md algo/baseline.md algo/gpg.md algo/rollout_corr.md algo/rollout_corr_math.md algo/otb.md algo/dppo.md algo/opd.md .. toctree:: :maxdepth: 1 :caption: PPO Trainer and Workers workers/ray_trainer workers/model_engine workers/engine_workers workers/automodel_workers workers/torchtitan_workers workers/sglang_worker workers/trtllm_worker .. toctree:: :maxdepth: 1 :caption: Performance Tuning Guide perf/dpsk.md perf/best_practices perf/perf_tuning perf/rollout_kv_offload.md README_vllm0.8.md perf/device_tuning perf/verl_profiler_system.md perf/nsight_profiling.md perf/torch_profiling.md .. toctree:: :maxdepth: 1 :caption: Adding new models advance/fsdp_extension advance/megatron_extension advance/deepseek_v4_integration advance/megatron_lite_backend .. toctree:: :maxdepth: 1 :caption: Async Training advance/one_step_off advance/delta_weight_sync advance/fully_async advance/async-on-policy-distill advance/dynamic_schedule .. toctree:: :maxdepth: 1 :caption: Low Precision low_precision/fp8.md low_precision/nvfp4_qat.md .. toctree:: :maxdepth: 1 :caption: Advanced Features advance/checkpoint advance/rope advance/attention_implementation advance/ppo_lora.rst sglang_multiturn/multiturn.rst advance/placement advance/dpo_extension examples/sandbox_fusion_example advance/rollout_trace.rst advance/rl_insight.md advance/skip_manager.rst advance/agent_loop advance/reward_loop data/transfer_queue.md advance/grafana_prometheus.md advance/mtp.md advance/determinism.md .. toctree:: :maxdepth: 1 :caption: Hardware Support hardware/multi_chip_support amd_tutorial/index.rst ascend_tutorial/index.rst .. toctree:: :maxdepth: 1 :caption: API References api/data api/single_controller.rst api/trainer.rst api/utils.rst .. toctree:: :maxdepth: 1 :caption: Blog blog/v0.7.md .. toctree:: :maxdepth: 2 :caption: FAQ faq/faq .. toctree:: :maxdepth: 1 :caption: Contributing contributing/editing-agent-instructions.md .. toctree:: :maxdepth: 1 :caption: Development Notes sglang_multiturn/sandbox_fusion.rst Contribution ------------- verl is free software; you can redistribute it and/or modify it under the terms of the Apache License 2.0. We welcome contributions. Join us on `GitHub `_, `Slack `_ and `Wechat `_ for discussions. Contributions from the community are welcome! Please check out our `project roadmap `_ and `good first issues `_ to see where you can contribute. Code Linting and Formatting ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ We use pre-commit to help improve code quality. To initialize pre-commit, run: .. code-block:: bash pip install pre-commit pre-commit install To resolve CI errors locally, you can also manually run pre-commit by: .. code-block:: bash pre-commit run Adding CI tests ^^^^^^^^^^^^^^^^^^^^^^^^ If possible, please add CI test(s) for your new feature: 1. Find the most relevant workflow yml file, which usually corresponds to a ``hydra`` default config (e.g. ``ppo_trainer``, ``ppo_megatron_trainer``, ``sft_trainer``, etc). 2. Add related path patterns to the ``paths`` section if not already included. 3. Minimize the workload of the test script(s) (see existing scripts for examples). We are HIRING! Send us an `email `_ if you are interested in internship/FTE opportunities in MLSys/LLM reasoning/multimodal alignment.