FastChat

FastChatSince 2026-08

FastChat is an open-source platform developed by LMSYS (Large Model Systems Organization) for training, serving, and evaluating large language model-based chatbots. As the technology powering the popular Chatbot Arena leaderboard, FastChat provides state-of-the-art serving infrastructure with OpenAI-compatible REST APIs, distributed worker orchestration, and Web UI interfaces. Machine learning engineers and enterprise developers use FastChat to self-host open-weights models (like Llama 3, Mistral, Vicuna, and DeepSeek) with multi-GPU acceleration and vLLM integration.

FastChat provides an end-to-end stack: high-throughput model serving workers, a central controller for load balancing across GPU nodes, and an OpenAI-compatible API server. It also includes comprehensive fine-tuning recipes using Hugging Face Transformers, DeepSpeed, and FlashAttention-2. FastChat is the gold standard foundation for organizations establishing sovereign, on-premise AI chat and API infrastructure.

Cosine GenieSince 2024-08

Cosine Genie is a next-generation autonomous software engineering agent built to tackle complex software bugs, refactors, and feature requests. Operating with deep semantic understanding of massive codebases, Genie analyzes repository architectures, creates comprehensive execution plans, and generates multi-file diffs that pass existing continuous integration test suites. Designed to bridge the gap between AI code completion and full software development lifecycle automation, Genie mimics human engineering workflows by navigating dependency graphs, testing assumptions in sandboxed environments, and autonomously self-correcting logic errors before opening pull requests.

Genie is powered by Cosine's proprietary fine-tuned reasoning models and multi-agent orchestration framework, benchmarked at top-tier performance on the industry-standard SWE-bench. The system integrates directly with GitHub and GitLab, indexing abstract syntax trees (ASTs), commit histories, and documentation to maintain contextual awareness. Its sandboxed runtime spins up localized build containers to execute unit tests, compile artifacts, and measure regression risks in real time. Engineering teams use Genie to triage backlogs, automate dependency upgrades, and accelerate code reviews with verified pull request generation.