8 Best FastChat Alternatives in 2026 (Open Source)

FastChat — An open platform for training, serving, and evaluating large language models. Release repo for Vicuna and Chatbot Arena.. Powers Chatbot Arena (lmarena.ai) with 10M+ chat requests and 1.5M+ human votes — the de facto platform for LLM evaluation via crowdsourced human preference, plus an OpenAI-compatible serving layer for 70+ models

These 8 open-source tools do the same job. They are ordered by how closely they match FastChat, with live GitHub data so you can see which projects are actively maintained.

1. 1. Text Generation Inference

   Large Language Model Text Generation Inference

   What sets it apart: Battle-tested in production at Hugging Face (powers HuggingChat and Inference API) — now in maintenance mode with recommendation to use vLLM/SGLang, but remains the reference implementation for optimized LLM serving with the broadest hardware support

   Best for: Production LLM serving with HuggingFace models at scale; Teams needing OpenAI-compatible API for open-source models

   ⭐ 10.9kFastChat vs Text Generation Inference →Full profile →

2. 2. vLLM

   A high-throughput and memory-efficient inference and serving engine for LLMs

   What sets it apart: Unlike llama.cpp (consumer-hardware focused, C++ native), vLLM is the production throughput king with PagedAttention achieving 2-24x higher throughput than HuggingFace Transformers on datacenter GPUs

   Best for: Production LLM serving requiring maximum throughput with PagedAttention and continuous batching; Teams serving multiple LoRA adapters from a single base model in production

   ⭐ 93.0kFastChat vs vLLM →Full profile →

3. 3. llama.cpp

   LLM inference in C/C++

   What sets it apart: Unlike vLLM (optimized for datacenter throughput), llama.cpp targets maximum hardware compatibility from Raspberry Pi to multi-GPU servers with the widest quantization range (1.5-bit to 8-bit)

   Best for: Running LLMs on consumer hardware with aggressive quantization (1.5-bit to 8-bit); Deploying OpenAI-compatible local API servers on edge devices or laptops

   ⭐ 130.0kFastChat vs llama.cpp →Full profile →

4. 4. llama-cpp-python

   Python bindings for llama.cpp

   What sets it apart: vs vLLM: optimized for local/edge deployment with GGUF quantized models on consumer hardware; vs Ollama: programmatic Python API with LangChain/LlamaIndex integration rather than CLI-first approach

   Best for: Running LLMs locally with Python; Building OpenAI-compatible local inference servers; Prototyping with quantized models on consumer hardware

   ⭐ 10.6kFastChat vs llama-cpp-python →Full profile →

5. 5. TextGen

   The original local LLM interface. Text, vision, tool-calling, training, and more. 100% offline.

   What sets it apart: Most feature-complete local LLM web UI with 4 inference backends, training, tool-calling, vision, and image gen — vs Ollama (CLI-focused) or LM Studio (closed source)

   Best for: Running any LLM locally with a full-featured web UI; Privacy-conscious users wanting 100% offline AI; Developers needing a local OpenAI-compatible API server

   ⭐ 47.7kFastChat vs TextGen →Full profile →

6. 6. Chat UI

   The open source codebase powering HuggingChat

   What sets it apart: Powers HuggingChat (huggingface.co/chat) — the most production-proven open-source chat UI with unique LLM Router for automatic model selection and native MCP tool support, unlike simpler UIs it handles multi-user, multi-model deployments

   Best for: Self-hosting a ChatGPT-like interface for open-source models; Organizations wanting HuggingChat-quality UI for their own LLMs

   ⭐ 11.0kFastChat vs Chat UI →Full profile →

7. 7. OpenChat

   LLMs custom-chatbots console ⚡

   What sets it apart: vs Chatbase/CustomGPT: self-hosted open-source chatbot platform with unlimited memory, codebase ingestion for pair programming, and embeddable website widgets — own your data without SaaS vendor lock-in

   Best for: Building knowledge-base chatbots from company documents; Website customer support widgets with custom data; Pair programming assistance using codebase context

   ⭐ 5.2kFastChat vs OpenChat →Full profile →

8. 8. Chatbot UI

   AI chat for any model.

   What sets it apart: vs ChatGPT web app: open-source, self-hosted with Supabase backend for full data ownership — the most popular open-source ChatGPT UI clone with 28k+ stars

   Best for: Developers wanting a self-hosted ChatGPT-like UI with data persistence; Teams needing an open-source chat interface they can customize; Organizations wanting full control over their AI chat data

   ⭐ 33.4kFastChat vs Chatbot UI →Full profile →