llmao

A fake OpenAI-compatible API server for local development and CI

npx llmao serve
llmao is pretending to be an LLM at http://127.0.0.1:4141

llmao serves /v1/chat/completions, /v1/messages (Anthropic), /v1/embeddings and /v1/models, with streaming, tool calls and structured output. Point any SDK at it:

from openai import OpenAI

client = OpenAI(base_url="http://127.0.0.1:4141/v1", api_key="llmao")
print(client.chat.completions.create(model="gpt-4o", messages=[{"role": "user", "content": "is 7 prime?"}]).choices[0].message.content)
# e.g. "Certainly! 7 is a prime number." (use --temperature 0 for plain answers)
curl http://127.0.0.1:4141/v1/chat/completions \
  -d '{"model":"gpt-4o","messages":[{"role":"user","content":"how many r are in strawberry?"}]}'

Scripted answers and failures

npx llmao serve --script script.json --failures rate_limit=0.05,server_error=0.01
[
  { "when": "/order\\s+#?\\d+/i", "text": "Your order has shipped." },
  { "when": "boom", "error": "server_error" }
]

In a JSON script, when can be a "/regex/flags" string. Failures come back with the real status codes and error bodies (429 with retry-after, 500, 504), so your SDK's retry logic runs.

Options

Flag
-p, --port Port (default 4141)
--host Host (default 127.0.0.1)
--script <file> Scripted answers
--failures <list> e.g. rate_limit=0.1,server_error=0.05,timeout=0.01
--speed instant, fast, realistic or dramatic
-m, --model Personality: lmao-1, lmao-safe, lmao-o1-overthinker…

In Node, start it from code with import { serve } from 'llmao/server' and await serve({ port: 0 }).

Related

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