--- title: "FastChat vs GPTRouter" type: "comparison" canonical_url: "https://www.graphcanon.com/compare/lm-sys-fastchat-vs-writesonic-gptrouter" tools: ["lm-sys-fastchat", "writesonic-gptrouter"] --- # FastChat vs GPTRouter *GraphCanon updated Aug 21, 2026* ## Verdict 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; pick GPTRouter if gPTRouter is notable for TypeScript and handles multiple LLMs and image models like OpenAI, Anthropic, Azure, Dall-E, SDXL with improved reliability and. [FastChat](https://github.com/lm-sys/FastChat) reports 40k GitHub stars, 4.8k forks, and 1.0k open issues, last pushed May 1, 2026. [GPTRouter](https://gpt-router.writesonic.com/) has 455 stars, 38 forks, and 10 open issues, last pushed Apr 10, 2024. Figures are from public GitHub metadata via [FastChat's repository](https://github.com/lm-sys/FastChat) and [GPTRouter's repository](https://github.com/Writesonic/GPTRouter). | | [FastChat](/tools/lm-sys-fastchat.md) | [GPTRouter](/tools/writesonic-gptrouter.md) | | --- | --- | --- | | Tagline | An open platform for training, serving, and evaluating large language models | Manage multiple LLMs and image models for reliable and fast responses | | Stars | 39,517 | 455 | | Forks | 4,788 | 38 | | Open issues | 1,038 | 10 | | Language | Python | TypeScript | | 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 | GPTRouter is notable for TypeScript and handles multiple LLMs and image models like OpenAI, Anthropic, Azure, Dall-E, SDXL with improved reliability and speed. | | Persona | - | - | | Runtime | - | - | | License | Apache-2.0 | The MIT license applies to GPTRouter, offering permissive use with conditions only requiring preservation of copyright and license notices. | | Categories | Evaluation & Observability, Inference & Serving, LLM Frameworks, Model Training | Inference & Serving, LLM Frameworks, Model Training | ## Trust and health _Sourced signals - not a safety guarantee. No winner column._ | | [FastChat](/tools/lm-sys-fastchat.md) | [GPTRouter](/tools/writesonic-gptrouter.md) | | --- | --- | --- | | Maintenance | Slowing (36%) | Dormant (18%) | | Days since push | 98d | 862d | | Open issues (now) | 1.0k | 10 | | Stars delta | Unknown | 0 (30d) | | Open issues delta | Unknown | 0 (30d) | | Full report | [trust report](/tools/lm-sys-fastchat/trust.md) | [trust report](/tools/writesonic-gptrouter/trust.md) | ## 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 ## Decision facts: GPTRouter - **Pricing:** freemium - GPTRouter is open-source under the MIT License. However, costs might arise from using associated models like OpenAI or Anthropic. - **Requirements:** Min 2 GB RAM - **Adopt for:** GPTRouter is notable for TypeScript and handles multiple LLMs and image models like OpenAI, Anthropic, Azure, Dall-E, SDXL with improved reliability and speed. - **License detail:** The MIT license applies to GPTRouter, offering permissive use with conditions only requiring preservation of copyright and license notices. ## Choose when ### Choose FastChat if… - FastChat is primarily Python; GPTRouter is TypeScript. - License: FastChat is Apache-2.0, GPTRouter is MIT. - Tags unique to FastChat: chatbots, distributed-serving, evaluation system, large language models. - Also covers Evaluation & Observability. - - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ### Choose GPTRouter if… - GPTRouter is primarily TypeScript; FastChat is Python. - License: GPTRouter is MIT, FastChat is Apache-2.0. - Pricing: GPTRouter is open-source under the MIT License. However, costs might arise from using associated models like OpenAI or Anthropic.. - Requirements: Min 2 GB RAM. - Tags unique to GPTRouter: anthropic, azure-openai, cohere, google-gemini. - GPTRouter ships Docker support for self-hosted deployment. - When your project requires seamless integration of different language models such as OpenAI, Anthropic, and Azure and demands reliability and fast response times. ## 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. ## When NOT to use GPTRouter - Avoid using GPTRouter if your project strictly uses Python without the flexibility to adopt TypeScript, as it may hinder seamless integration. - If your application exclusively focuses on a single LLM or image model provider lacking the need for managing multiple providers, consider alternatives more focused in scope and potentially lighter. ## Common questions ### What is the difference between FastChat and GPTRouter? FastChat: An open platform for training, serving, and evaluating large language models. GPTRouter: Manage multiple LLMs and image models for reliable and fast responses. See the comparison table for live GitHub stats and shared categories. ### When should I choose FastChat over GPTRouter? Choose FastChat over GPTRouter when FastChat is primarily Python; GPTRouter is TypeScript; License: FastChat is Apache-2.0, GPTRouter is MIT; Tags unique to FastChat: chatbots, distributed-serving, evaluation system, large language models; Also covers Evaluation & Observability; - You are looking to train and evaluate state-of-the-art models such as Vicuna or MT-Bench. ### When should I choose GPTRouter over FastChat? Choose GPTRouter over FastChat when GPTRouter is primarily TypeScript; FastChat is Python; License: GPTRouter is MIT, FastChat is Apache-2.0; Pricing: GPTRouter is open-source under the MIT License. However, costs might arise from using associated models like OpenAI or Anthropic.; Requirements: Min 2 GB RAM; Tags unique to GPTRouter: anthropic, azure-openai, cohere, google-gemini; GPTRouter ships Docker support for self-hosted deployment; When your project requires seamless integration of different language models such as OpenAI, Anthropic, and Azure and demands reliability and fast response times. ### 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. ### When should I avoid GPTRouter? Avoid using GPTRouter if your project strictly uses Python without the flexibility to adopt TypeScript, as it may hinder seamless integration. If your application exclusively focuses on a single LLM or image model provider lacking the need for managing multiple providers, consider alternatives more focused in scope and potentially lighter. ### Is FastChat or GPTRouter more popular on GitHub? FastChat has more GitHub stars (39,517 vs 455). Stars measure visibility, not whether either tool fits your constraints. ### Are FastChat and GPTRouter open source? Yes - both are open-source projects on GitHub (FastChat: Apache-2.0, GPTRouter: MIT). ### Where can I find alternatives to FastChat or GPTRouter? GraphCanon lists graph-backed alternatives at [FastChat alternatives](/tools/lm-sys-fastchat/alternatives) and [GPTRouter alternatives](/tools/writesonic-gptrouter/alternatives) ([FastChat markdown twin](/tools/lm-sys-fastchat/alternatives.md), [GPTRouter markdown twin](/tools/writesonic-gptrouter/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/lm-sys-fastchat-vs-writesonic-gptrouter.md) mirrors this page for agents and LLM crawlers, with the same stats table and FAQ answers. ### Which is better maintained, FastChat or GPTRouter? FastChat: Slowing. GPTRouter: Dormant. 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 FastChat and GPTRouter? GraphCanon publishes per-repo trust reports with dated maintenance, provenance, and scan summaries: [FastChat trust report](/tools/lm-sys-fastchat/trust); [GPTRouter trust report](/tools/writesonic-gptrouter/trust). --- **Machine-readable endpoints** - JSON: [`/api/graphcanon/graph?tool=lm-sys-fastchat`](/api/graphcanon/graph?tool=lm-sys-fastchat) - 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/_