--- title: "chatllm.cpp vs FastChat" type: "comparison" canonical_url: "https://www.graphcanon.com/compare/foldl-chatllm-cpp-vs-lm-sys-fastchat" tools: ["foldl-chatllm-cpp", "lm-sys-fastchat"] --- # chatllm.cpp vs FastChat *GraphCanon updated Aug 25, 2026* ## Verdict Pick chatllm.cpp if this C++ library aims to deploy language models for real-time chatting on local systems with support for CPU and GPU; pick FastChat if fastChat is a comprehensive open platform for managing large language models (LLMs) that includes capabilities for training, serving, evaluating, and comparing chatbot models via web UIs and RESTful APIs. It powers ChatB. [chatllm.cpp](https://github.com/foldl/chatllm.cpp) reports 917 GitHub stars, 72 forks, and 11 open issues, last pushed Aug 22, 2026. [FastChat](https://github.com/lm-sys/FastChat) has 40k stars, 4.8k forks, and 1.0k open issues, last pushed May 1, 2026. Figures are from public GitHub metadata via [chatllm.cpp's repository](https://github.com/foldl/chatllm.cpp) and [FastChat's repository](https://github.com/lm-sys/FastChat). | | [chatllm.cpp](/tools/foldl-chatllm-cpp.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Tagline | C++ real-time chat models for CPU and GPU | An open platform for training, serving, and evaluating large language models | | Stars | 917 | 39,517 | | Forks | 72 | 4,788 | | Open issues | 11 | 1,038 | | Language | C++ | Python | | Adopt for | This C++ library aims to deploy language models for real-time chatting on local systems with support for CPU and GPU. | FastChat is a comprehensive open platform for managing large language models (LLMs) that includes capabilities for training, serving, evaluating, and comparing chatbot models via web UIs and RESTful APIs. It powers ChatB | | Persona | - | - | | Runtime | - | - | | License | MIT | Apache-2.0 | | Categories | Inference & Serving, LLM Frameworks | Evaluation & Observability, Inference & Serving, LLM Frameworks, Model Training | ## Trust and health _Sourced signals - not a safety guarantee. No winner column._ | | [chatllm.cpp](/tools/foldl-chatllm-cpp.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Maintenance | Very active (96%) | Slowing (36%) | | Days since push | 2d | 98d | | Open issues (now) | 11 | 1.0k | | Stars delta | +5 (30d) | Unknown | | Open issues delta | 0 (30d) | Unknown | | Owner type | User | Organization | | Full report | [trust report](/tools/foldl-chatllm-cpp/trust.md) | [trust report](/tools/lm-sys-fastchat/trust.md) | ## Shared compatibility - **Python**: [chatllm.cpp](/tools/foldl-chatllm-cpp.md) - Python runtime; [FastChat](/tools/lm-sys-fastchat.md) - Python runtime ## Decision facts: chatllm.cpp - **Adopt for:** This C++ library aims to deploy language models for real-time chatting on local systems with support for CPU and GPU. ## Decision facts: FastChat - **Adopt for:** FastChat is a comprehensive open platform for managing large language models (LLMs) that includes capabilities for training, serving, evaluating, and comparing chatbot models via web UIs and RESTful APIs. It powers ChatB ## Choose when ### Choose chatllm.cpp if… - chatllm.cpp is primarily C++; FastChat is Python. - License: chatllm.cpp is MIT, FastChat is Apache-2.0. - Tags unique to chatllm.cpp: cpu-support, gpu-support, llm, llm-inference. - When you need a C++ framework that can integrate tightly into existing C++ applications requiring fast chat responses. ### Choose FastChat if… - FastChat is primarily Python; chatllm.cpp is C++. - License: FastChat is Apache-2.0, chatllm.cpp is MIT. - Tags unique to FastChat: chatbots, distributed-serving, evaluation system, large language models. - Also covers Evaluation & Observability, Model Training. - - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ## When NOT to use chatllm.cpp - Avoid if your preferred development environment is centered around high-level languages such as Python, where alternatives like Transformers are robust and well-supported. - Not suitable for projects that require a wide array of pre-trained models not provided by chatllm.cpp itself, since it does not include model training functionalities. ## When NOT to use FastChat - - You require a proprietary or closed-source framework; FastChat is open-source under Apache-2.0 license and its use might be unsuitable for environments requiring proprietary solutions. - - Your chatbot evaluation needs do not align with the types of data used in FastChat's datasets (e.g., human votes, MT-Bench evaluations). - - You prefer a more user-friendly setup without the need to clone a repository and manually install dependencies; FastChat requires installation from source with additional steps for Rust and CMake on - + Mac. ## Common questions ### What is the difference between chatllm.cpp and FastChat? chatllm.cpp: C++ real-time chat models for CPU and GPU. FastChat: An open platform for training, serving, and evaluating large language models. See the comparison table for live GitHub stats and shared categories. ### When should I choose chatllm.cpp over FastChat? Choose chatllm.cpp over FastChat when chatllm.cpp is primarily C++; FastChat is Python; License: chatllm.cpp is MIT, FastChat is Apache-2.0; Tags unique to chatllm.cpp: cpu-support, gpu-support, llm, llm-inference; When you need a C++ framework that can integrate tightly into existing C++ applications requiring fast chat responses. ### When should I choose FastChat over chatllm.cpp? Choose FastChat over chatllm.cpp when FastChat is primarily Python; chatllm.cpp is C++; License: FastChat is Apache-2.0, chatllm.cpp is MIT; Tags unique to FastChat: chatbots, distributed-serving, evaluation system, large language models; Also covers Evaluation & Observability, Model Training; - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ### When should I avoid chatllm.cpp? Avoid if your preferred development environment is centered around high-level languages such as Python, where alternatives like Transformers are robust and well-supported. Not suitable for projects that require a wide array of pre-trained models not provided by chatllm.cpp itself, since it does not include model training functionalities. ### When should I avoid FastChat? - You require a proprietary or closed-source framework; FastChat is open-source under Apache-2.0 license and its use might be unsuitable for environments requiring proprietary solutions. - Your chatbot evaluation needs do not align with the types of data used in FastChat's datasets (e.g., human votes, MT-Bench evaluations). - You prefer a more user-friendly setup without the need to clone a repository and manually install dependencies; FastChat requires installation from source with additional steps for Rust and CMake on + Mac. ### Is chatllm.cpp or FastChat more popular on GitHub? FastChat has more GitHub stars (39,517 vs 917). Stars measure visibility, not whether either tool fits your constraints. ### Are chatllm.cpp and FastChat open source? Yes - both are open-source projects on GitHub (chatllm.cpp: MIT, FastChat: Apache-2.0). ### Where can I find alternatives to chatllm.cpp or FastChat? GraphCanon lists graph-backed alternatives at [chatllm.cpp alternatives](/tools/foldl-chatllm-cpp/alternatives) and [FastChat alternatives](/tools/lm-sys-fastchat/alternatives) ([chatllm.cpp markdown twin](/tools/foldl-chatllm-cpp/alternatives.md), [FastChat markdown twin](/tools/lm-sys-fastchat/alternatives.md)), ranked by typed relationship edges rather than popularity votes. ### Is there a machine-readable version of this comparison? Yes. The markdown twin at [this comparison](/compare/foldl-chatllm-cpp-vs-lm-sys-fastchat.md) mirrors this page for agents and LLM crawlers, with the same stats table and FAQ answers. ### Which is better maintained, chatllm.cpp or FastChat? chatllm.cpp: Very active. FastChat: Slowing. Compare maintenance labels, days since push, and release cadence in the trust section below - stars alone do not measure maintenance. ### Where are the full trust reports for chatllm.cpp and FastChat? GraphCanon publishes per-repo trust reports with dated maintenance, provenance, and scan summaries: [chatllm.cpp trust report](/tools/foldl-chatllm-cpp/trust); [FastChat trust report](/tools/lm-sys-fastchat/trust). --- **Machine-readable endpoints** - JSON: [`/api/graphcanon/graph?tool=foldl-chatllm-cpp`](/api/graphcanon/graph?tool=foldl-chatllm-cpp) - LLM index: [/llms.txt](/llms.txt) - Full corpus: [/llms-full.txt](/llms-full.txt) _GraphCanon - The knowledge graph for AI development. https://www.graphcanon.com/_