Arch-Router – 1.5B model for LLM routing by preferences, not benchmarks

In plain words

Arch-Router is a 1.5B model that intelligently routes prompts to different large language models based on user preferences rather than task classification. Built by the team behind Arch, an open-source LLM proxy written in Rust, it addresses the challenge of directing requests to the right model when teams use multiple LLMs with different strengths, costs, and latencies. The router is designed for developers building applications with multiple LLM backends who need dynamic routing that adapts to real conversations rather than fixed categories.

written from the facts on this page · September 2026

From the sources

Abstract page for arXiv paper 2506.16655: Arch-Router: Aligning LLM Routing with Human Preferences

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In the maker’s words, at launch

Hi HN — we're the team behind Arch (https://github.com/katanemo/archgw), an open-source proxy for LLMs written in Rust. Today we're releasing Arch-Router (https://huggingface.co/katanemo/Arch-Router-1.5B), a 1.5B router model for preference-based routing, now integrated into…

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  Arch2024 · github.com · ▲314

  Hey HN — I’m Adil from Katanemo (with Salman, Shuguang, and Meiyu) We previously shared an early version of this project as ArchGW. Based on customer feedback, the scope expanded from “LLM routing and model access” into something broader: delivery infrastructure for agentic applications. We renamed it to Plano and reworked the architecture accordingly. The problem On-the-ground AI practitioners will tell you that calling an LLM is not the hard part. The really hard part is delivering agentic applications to production quickly and reliably, then iterating without rewriting system code every…

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• RY
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