Release: llm-chat-completions-server 0.1a0
Simon Willison’s Weblog
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30th July 2026
Release
llm-chat-completions-server 0.1a0 — LLM plugin to serve an OpenAI Chat Completions API endpoint
A key goal of the new content-addressable logs in LLM 0.32rc1 was being able to support OpenAI Chat Completion style requests where each incoming message extends the previous conversation, like this:
curl http://localhost:8002/v1/chat/completions \ -H 'Content-Type: application/json' \ -d '{ "model": "qwen3.5-4b", "messages": [ {"role": "user", "content": "Capital of France?"}, {"role": "assistant", "content": "Paris."}, {"role": "user", "content": "Germany?"} ] }'
Here the conversation state is tracked by the client, so each of these requests gets longer and longer. The new schema design in LLM is designed to de-duplicate these using hashes of the individual message parts.
To test that out, I built this plugin:
uv tool install llm --pre llm install llm-chat-completions-server llm chat-completions-server -p 9001
Running this starts a localhost server on port 9001 that exposes your full collection of LLM models (from any plugins you have installed) using a ChatGPT Completions compatible endpoint.
GPT-5.6 Sol wrote the whole thing - it turns out it knows the OpenAI Chat Completions API shape really well.
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This is a beat by Simon Willison, posted on 30th July 2026.
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