--- title: "openchat vs FastChat" type: "comparison" canonical_url: "https://www.graphcanon.com/compare/imoneoi-openchat-vs-lm-sys-fastchat" tools: ["imoneoi-openchat", "lm-sys-fastchat"] --- # openchat vs FastChat *GraphCanon updated Aug 17, 2026* ## Verdict Pick openchat if a Python library for training large language models with imperfect data using transformers; 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. [openchat](https://openchat.team) reports 5.5k GitHub stars, 432 forks, and 137 open issues, last pushed Sep 13, 2024. [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 [openchat's repository](https://github.com/imoneoi/openchat) and [FastChat's repository](https://github.com/lm-sys/FastChat). | | [openchat](/tools/imoneoi-openchat.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Tagline | Advancing Open-source Language Models with Imperfect Data | An open platform for training, serving, and evaluating large language models | | Stars | 5,487 | 39,517 | | Forks | 432 | 4,788 | | Open issues | 137 | 1,038 | | Language | Python | Python | | Adopt for | A Python library for training large language models with imperfect data using transformers. | 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 | LLM Frameworks, Model Training | Evaluation & Observability, Inference & Serving, LLM Frameworks, Model Training | ## Trust and health _Sourced signals - not a safety guarantee. No winner column._ | | [openchat](/tools/imoneoi-openchat.md) | [FastChat](/tools/lm-sys-fastchat.md) | | --- | --- | --- | | Maintenance | Dormant (18%) | Slowing (36%) | | Days since push | 703d | 98d | | Open issues (now) | 137 | 1.0k | | Stars delta | +2 (30d) | Unknown | | Open issues delta | +1 (30d) | Unknown | | Owner type | User | Organization | | Full report | [trust report](/tools/imoneoi-openchat/trust.md) | [trust report](/tools/lm-sys-fastchat/trust.md) | ## Decision facts: openchat - **Adopt for:** A Python library for training large language models with imperfect data using transformers. ## 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 openchat if… - Tags unique to openchat: apache license 2.0, cuda, open-source, pytorch. - You need to train models on datasets with noise or missing information - Leaner open-issue backlog (137). ### Choose FastChat if… - Tags unique to FastChat: chatbots, distributed-serving, evaluation system. - Also covers Evaluation & Observability, Inference & Serving. - - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ## When NOT to use openchat - If your dataset is clean and well-structured, reducing model inaccuracies - Projects that cannot depend on Apache License 2.0 or install PyTorch with CUDA support ## 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 openchat and FastChat? openchat: Advancing Open-source Language Models with Imperfect Data. 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 openchat over FastChat? Choose openchat over FastChat when Tags unique to openchat: apache license 2.0, cuda, open-source, pytorch; You need to train models on datasets with noise or missing information; Leaner open-issue backlog (137). ### When should I choose FastChat over openchat? Choose FastChat over openchat when Tags unique to FastChat: chatbots, distributed-serving, evaluation system; Also covers Evaluation & Observability, Inference & Serving; - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ### When should I avoid openchat? If your dataset is clean and well-structured, reducing model inaccuracies Projects that cannot depend on Apache License 2.0 or install PyTorch with CUDA support ### 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 openchat or FastChat more popular on GitHub? FastChat has more GitHub stars (39,517 vs 5,487). Stars measure visibility, not whether either tool fits your constraints. ### Are openchat and FastChat open source? Yes - both are open-source projects on GitHub (openchat: Apache-2.0, FastChat: Apache-2.0). ### Where can I find alternatives to openchat or FastChat? GraphCanon lists graph-backed alternatives at [openchat alternatives](/tools/imoneoi-openchat/alternatives) and [FastChat alternatives](/tools/lm-sys-fastchat/alternatives) ([openchat markdown twin](/tools/imoneoi-openchat/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/imoneoi-openchat-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, openchat or FastChat? openchat: Dormant. 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 openchat and FastChat? GraphCanon publishes per-repo trust reports with dated maintenance, provenance, and scan summaries: [openchat trust report](/tools/imoneoi-openchat/trust); [FastChat trust report](/tools/lm-sys-fastchat/trust). --- **Machine-readable endpoints** - JSON: [`/api/graphcanon/graph?tool=imoneoi-openchat`](/api/graphcanon/graph?tool=imoneoi-openchat) - 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/_