OpenAI-compatible API for open models: change the base URL

Munito AI is an OpenAI-compatible API for open models, and it also serves the Anthropic Messages API. To move an app to Munito AI, keep your OpenAI or Anthropic SDK and change three values: the base URL, the API key and the model name. The request and response formats stay the same, so the rest of your code does not change.

The Anthropic SDK adds /v1/messages itself, so its base URL has no /v1. Create a key in the console and export it:

export MUNITO_API_KEY="munitoai_..."

OpenAI SDK in PythonCopy Anchor Link

pip install openai

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.munito.ai/inference/v1",
    api_key=os.environ["MUNITO_API_KEY"],
)
response = client.chat.completions.create(
    model="qwen/qwen3.8-27b",
    messages=[{"role": "user", "content": "Name three rivers in Europe."}],
    max_tokens=2048,
)
print(response.choices[0].message.content)

OpenAI SDK in TypeScriptCopy Anchor Link

npm install openai

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.munito.ai/inference/v1",
  apiKey: process.env.MUNITO_API_KEY,
});
const response = await client.chat.completions.create({
  model: "qwen/qwen3.8-27b",
  messages: [{ role: "user", content: "Name three rivers in Europe." }],
  max_tokens: 2048,
});
console.log(response.choices[0].message.content);

Anthropic SDK in PythonCopy Anchor Link

pip install anthropic

import os
from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.munito.ai/inference",
    api_key=os.environ["MUNITO_API_KEY"],
)
message = client.messages.create(
    model="qwen/qwen3.8-27b",
    max_tokens=2048,
    messages=[{"role": "user", "content": "Name three rivers in Europe."}],
)
for block in message.content:
    if block.type == "text":
        print(block.text)

The answer also holds a thinking block before the text block, because the model reasons first. See Reasoning.

Model namesCopy Anchor Link

Munito AI names each model <organization>/<model>. Replace your OpenAI or Anthropic model name with one of these:

The model catalog has the details of each model, and GET /inference/v1/models lists the models that your key can use. A model name that Munito AI does not serve returns 404 with code model_not_found:

{
  "error": {
    "message": "The model gpt-4o does not exist, or you do not have access to it.",
    "type": "invalid_request_error",
    "param": "model",
    "code": "model_not_found"
  }
}

EndpointsCopy Anchor Link

Each path starts with https://api.munito.ai/inference. Munito AI has no embeddings endpoint and no file upload endpoint. A path that Munito AI does not serve returns 404 with the detail No API operation has this path.

What works differentlyCopy Anchor Link

Munito AI never ignores a parameter in silence. A parameter that it cannot apply returns 400, so that you know at once.

Chat CompletionsCopy Anchor Link

Munito AI also accepts top_k, repetition_penalty and chat_template_kwargs. min_p works on aleph-alpha/kolibri-1 only.

A rejected parameter returns a message in this form:

{
  "error": {
    "message": "'web_search_options' is not supported: hosted web search is not available",
    "type": "invalid_request_error",
    "param": "web_search_options",
    "code": null
  }
}

A parameter that no API knows returns unknown parameter: 'name'.

ResponsesCopy Anchor Link

• Function tools work. A hosted web search tool is removed from the request, and the model answers without a search. Other hosted tools return 400.
• Munito AI stores a response only when you send store: true (or background: true). OpenAI stores by default, so add store: true where your code uses previous_response_id. Without it, the chained request returns 400 with previous response resp_... was not stored. Send store: true to continue a response.
• conversation, prompt, max_tool_calls, context_management, stream_options, prompt_cache_retention and text.verbosity return 400.
• include accepts only message.output_text.logprobs and reasoning.encrypted_content.

MessagesCopy Anchor Link

• The request accepts model, messages, system, max_tokens, metadata, stop_sequences, stream, temperature, top_p, top_k, tools, tool_choice, thinking, output_config and chat_template_kwargs. Another field returns 400 with unknown messages parameter: <name>.
• max_tokens is required. A value above the model maximum is lowered to the maximum.
• tools accepts only your own tools. A server tool, such as web search, returns 'tools' is not supported: only function tools are available.
• thinking.budget_tokens is accepted, but the model does not keep to it. max_tokens limits the whole output.
• context_management is accepted and has no effect.
• To choose a service tier, send the munito-service-tier header.

Reasoning modelsCopy Anchor Link

The public chat models reason before they answer by default, except google/gemma-4-12b. The reasoning uses output tokens, and it comes before the answer. Set max_tokens to 2048 or more. With a small value, the output can stop during the reasoning, and content is then null. See Reasoning to lower or turn off the reasoning.

Errors and headersCopy Anchor Link

Each API returns errors in its own format: OpenAI's {"error": {...}} on the OpenAI endpoints, and Anthropic's {"type": "error", ...} on Messages. The SDKs therefore raise their usual exception types. Rate limits return 429, and a model with no free capacity returns 503. See Rate limits.