Use OpenRouter with a coding agent

Export OPENROUTER_API_KEY and run oharness -m openrouter/<vendor>/<model>. OHarness discovers OpenRouter's model list, so every model it routes is available under /models.

Three commands

$npm install -g oharness

$export OPENROUTER_API_KEY="..."

$oharness

Then /models to see what OpenRouter offers and /model openrouter/<vendor>/<model> to pick one — the model id is OpenRouter's own, which already contains a slash.

When OpenRouter is the right choice

Trying many models without opening an account with each vendor.
One bill and one key for a team that uses several vendors.
Fallback: if one upstream is down, the next turn can go to another through the same key.

Worth knowing

Buying OpenRouter credits carries a fee, so a vendor's direct API can be cheaper for heavy use of one model.
OHarness identifies itself to OpenRouter as OHarness in the request headers, so usage appears under that app on OpenRouter.
Mixing is fine: DeepSeek through its own key and Claude through OpenRouter, in one session.

Common questions

Can I use OpenRouter with a Claude Code-style coding agent?

Yes. OHarness has OpenRouter as a built-in provider. Set OPENROUTER_API_KEY and pick any model with /model openrouter/<vendor>/<model>.

Does switching OpenRouter models mid-session lose context?

Not in OHarness. History is stored vendor-neutral, so moving between models behind OpenRouter — or between OpenRouter and a direct provider — converts nothing.

OpenRouter reference

Provider id	`openrouter`
Base URL	`https://openrouter.ai/api/v1`
Protocol	OpenAI-compatible chat completions
API key	`OPENROUTER_API_KEY`
Model discovery	Yes — the model list is asked of the endpoint rather than shipped.

Connecting it

The endpoint above is built in, so there is nothing to configure. Put the key in the environment and the provider appears in the model picker:

$export OPENROUTER_API_KEY="..."

Keys are issued by OpenRouter — where to get one.

Pointing it somewhere else

A regional host, a gateway, or a server of your own. Overrides in ~/.oharness/config.json are field level, so changing the endpoint does not mean restating the rest of the provider — this is the whole block, shown holding the default so the shape is clear:

{
  "providers": {
    "openrouter": {
      "baseUrl": "https://openrouter.ai/api/v1"
    }
  }
}

What you get either way

The same agent loop, the same tools, the same MCP servers and the same permission rules, whichever provider is underneath — and switching between them mid-session converts nothing, because history is never stored in a vendor’s shape. What an agent harness is covers why that is the hard part, and the providers reference covers the catalogue itself.

All 34 providers · Install OHarness