--- title: "CosyVoice vs FastChat" type: "comparison" canonical_url: "https://www.graphcanon.com/compare/funaudiollm-cosyvoice-vs-lm-sys-fastchat" tools: ["funaudiollm-cosyvoice", "lm-sys-fastchat"] --- # CosyVoice vs FastChat *GraphCanon updated Jul 12, 2026* ## Verdict Pick CosyVoice if cosyVoice is a Python-based multi-lingual large voice generation model. It supports extensive capabilities including fine-tuning, TTS (Text-To-Speech), and natural language generation; 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. [CosyVoice](https://funaudiollm.github.io/cosyvoice3) reports 22k GitHub stars, 2.5k forks, and 767 open issues, last pushed May 25, 2026. [FastChat](https://github.com/lm-sys/FastChat) has 39k stars, 4.8k forks, and 1.0k open issues, last pushed May 1, 2026. Figures are from public GitHub metadata via [CosyVoice's repository](https://github.com/FunAudioLLM/CosyVoice) and [FastChat's repository](https://github.com/lm-sys/FastChat). | | [CosyVoice](/tools/funaudiollm-cosyvoice.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Tagline | Multi-lingual large voice generation model with full-stack abilities for inference, training and deployment. | An open platform for training, serving, and evaluating large language models | | Stars | 22,089 | 39,490 | | Forks | 2,545 | 4,788 | | Open issues | 767 | 1,027 | | Language | Python | Python | | Adopt for | CosyVoice is a Python-based multi-lingual large voice generation model. It supports extensive capabilities including fine-tuning, TTS (Text-To-Speech), and natural language generation. | 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 | Apache-2.0 | Apache-2.0 | | Categories | Model Training, Inference & Serving, Speech & Audio | LLM Frameworks, Model Training, Inference & Serving, Evaluation & Observability | ## Trust and health _Sourced signals - not a safety guarantee. No winner column._ | | [CosyVoice](/tools/funaudiollm-cosyvoice.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Days since push | 46d | 71d | | Open issues (now) | 767 | 1.0k | | Full report | [trust report](/tools/funaudiollm-cosyvoice/trust.md) | [trust report](/tools/lm-sys-fastchat/trust.md) | ## Decision facts: CosyVoice - **Adopt for:** CosyVoice is a Python-based multi-lingual large voice generation model. It supports extensive capabilities including fine-tuning, TTS (Text-To-Speech), and natural language generation. ## 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 CosyVoice if… - Tags unique to CosyVoice: cantonese, audio-generation, chinese, english. - Also covers Speech & Audio. - When you need support for multiple languages like Cantonese, Chinese, English, Japanese, and Korean. ### Choose FastChat if… - Tags unique to FastChat: evaluation system, large-language-models, chatbots, distributed serving. - Also covers LLM Frameworks, Evaluation & Observability. - - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ## When NOT to use CosyVoice - If your project specifically requires fine-tuned performance in languages not supported by CosyVoice such as Arabic or Spanish. - When strict real-time speech synthesis requirements are essential, as CosyVoice may face delays depending on the environment's computational power and model complexity. ## 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 CosyVoice and FastChat? CosyVoice: Multi-lingual large voice generation model with full-stack abilities for inference, training and deployment.. 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 CosyVoice over FastChat? Choose CosyVoice over FastChat when Tags unique to CosyVoice: cantonese, audio-generation, chinese, english; Also covers Speech & Audio; When you need support for multiple languages like Cantonese, Chinese, English, Japanese, and Korean. ### When should I choose FastChat over CosyVoice? Choose FastChat over CosyVoice when Tags unique to FastChat: evaluation system, large-language-models, chatbots, distributed serving; Also covers LLM Frameworks, Evaluation & Observability; - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ### When should I avoid CosyVoice? If your project specifically requires fine-tuned performance in languages not supported by CosyVoice such as Arabic or Spanish. When strict real-time speech synthesis requirements are essential, as CosyVoice may face delays depending on the environment's computational power and model complexity. ### 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 CosyVoice or FastChat more popular on GitHub? FastChat has more GitHub stars (39,490 vs 22,089). Stars measure visibility, not whether either tool fits your constraints. ### Are CosyVoice and FastChat open source? Yes - both are open-source projects on GitHub (CosyVoice: Apache-2.0, FastChat: Apache-2.0). ### Where can I find alternatives to CosyVoice or FastChat? GraphCanon lists graph-backed alternatives at [CosyVoice alternatives](/tools/funaudiollm-cosyvoice/alternatives) and [FastChat alternatives](/tools/lm-sys-fastchat/alternatives) ([CosyVoice markdown twin](/tools/funaudiollm-cosyvoice/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/funaudiollm-cosyvoice-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, CosyVoice or FastChat? CosyVoice: Steady. FastChat: Steady. 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 CosyVoice and FastChat? GraphCanon publishes per-repo trust reports with dated maintenance, provenance, and scan summaries: [CosyVoice trust report](/tools/funaudiollm-cosyvoice/trust); [FastChat trust report](/tools/lm-sys-fastchat/trust). --- **Machine-readable endpoints** - JSON: [`/api/graphcanon/graph?tool=funaudiollm-cosyvoice`](/api/graphcanon/graph?tool=funaudiollm-cosyvoice) - 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/_