Simon Willison’s Weblog

llm-openrouter 0.4. I found out this morning that OpenRouter include support for a number of (rate-limited) free API models.

I occasionally run workshops on top of LLMs (like this one) and being able to provide students with a quick way to obtain an API key against models where they don't have to setup billing is really valuable to me!

This inspired me to upgrade my existing llm-openrouter plugin, and in doing so I closed out a bunch of open feature requests.

Consider this post the annotated release notes:

• LLM schema support for OpenRouter models that support structured output. #23

I'm trying to get support for LLM's new schema feature into as many plugins as possible.

OpenRouter's OpenAI-compatible API includes support for the response_format structured content option, but with an important caveat: it only works for some models, and if you try to use it on others it is silently ignored.

I filed an issue with OpenRouter requesting they include schema support in their machine-readable model index. For the moment LLM will let you specify schemas for unsupported models and will ignore them entirely, which isn't ideal.

• llm openrouter key command displays information about your current API key. #24

Useful for debugging and checking the details of your key's rate limit.

• llm -m ... -o online 1 enables web search grounding against any model, powered by Exa. #25

OpenRouter apparently make this feature available to every one of their supported models! They're using new-to-me Exa to power this feature, an AI-focused search engine startup who appear to have built their own index with their own crawlers (according to their FAQ). This feature is currently priced by OpenRouter at $4 per 1000 results, and since 5 results are returned for every prompt that's 2 cents per prompt.

• llm openrouter models command for listing details of the OpenRouter models, including a --json option to get JSON and a --free option to filter for just the free models. #26

This offers a neat way to list the available models. There are examples of the output in the comments on the issue.

• New option to specify custom provider routing: -o provider '{JSON here}'. #17

Part of OpenRouter's USP is that it can route prompts to different providers depending on factors like latency, cost or as a fallback if your first choice is unavailable - great for if you are using open weight models like Llama which are hosted by competing companies.

The options they provide for routing are very thorough - I had initially hoped to provide a set of CLI options that covered all of these bases, but I decided instead to reuse their JSON format and forward those options directly on to the model.