Show HN: FusionHarness – An Open-source Mixture-of-Agents compound-model server

Category: ai-ml

Tags: mixture-of-agents, llm, openai-compatible-server

Score: 6.3/10 (Innovation: 6, Technical: 6, Documentation: 7, Utility: 6)

FusionHarness is an open-source Mixture-of-Agents server that fans out prompts to multiple LLMs in parallel, then uses a judge and synthesizer to produce a final answer that often surpasses any single model. It's interesting because it offers a self-hosted alternative to OpenRouter's Fusion API, with support for tool use, agentic coding, and cost tracking, making advanced multi-model reasoning accessible for custom workflows.

Target audience: backend devs, data engineers

Repository: https://github.com/jackulau/fusionHarness · Python · MIT

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