Point a coding agent or runtime at BitRouter — Claude Code, Codex, OpenCode, DeepSeek Harness, Pi — and run it on any model in the registry.

A harness is the agent runtime that drives the loop — the CLI or service that reads your prompt, calls tools, and edits files. Each one already speaks some model API; the move is always the same: point it at BitRouter's endpoint (local proxy at http://127.0.0.1:4356, or Cloud at https://api.bitrouter.ai) instead of the vendor's, and address models by their provider/model id. From there the same harness can run on Anthropic, OpenAI, Google, or an open model — with provider selection and fallback underneath.

Claude Code

Anthropic Messages via ANTHROPIC_BASE_URL

Codex

Spawn wrapper or custom provider

OpenCode

Provider block in opencode.json

DeepSeek Harness

Custom provider route in settings.yaml

Pi

Minimal terminal coding harness via models.json

Harness vs. model source

Two of these share a name with a model source, and it's worth keeping them straight:

You want to…	Use
Run the Claude Code CLI on any model	Claude Code (harness)
Spend your Claude plan as tokens	Claude subscription (model)
Run the Codex CLI on any model	Codex (harness)
Spend your ChatGPT plan as tokens	Codex subscription (model)

A harness is what runs; a model source is where the tokens come from. You can combine them freely — e.g. drive Claude Code (harness) against your ChatGPT plan (Codex subscription), or against a local Ollama model.

New to BitRouter?

Start with the Quick Start to get the proxy running, then come back and point your harness at it.

Overview