onlist 0.1.0

Official Python SDK for Onlist, the AI API marketplace. Access GPT, Claude, Gemini, DeepSeek and 40+ models through one OpenAI-compatible API.

Onlist Python SDK

The official Python client for Onlist, the AI API marketplace.

Onlist aggregates 40+ AI model providers behind a single OpenAI-compatible API. This SDK is a drop-in replacement for the OpenAI Python client, so you can switch with one line of code.

Installation

pip install onlist

Quick Start

from onlist import Onlist

client = Onlist(api_key="sk-...")  # or set ONLIST_API_KEY env var

response = client.chat.completions.create(
    model="anthropic/claude-sonnet-4",
    messages=[{"role": "user", "content": "What is Onlist?"}],
)
print(response.choices[0].message.content)

Get your API key at onlist.io.

Authentication

The client reads your API key from:

1. The api_key parameter
2. The ONLIST_API_KEY environment variable
3. The OPENAI_API_KEY environment variable (fallback, for easy migration)

export ONLIST_API_KEY="sk-..."

Provider Routing

Onlist's marketplace lets you choose which provider serves your request. Use the provider field via extra_body:

# Pin to a specific provider
response = client.chat.completions.create(
    model="anthropic/claude-sonnet-4",
    messages=[{"role": "user", "content": "Hello"}],
    extra_body={"provider": "alice-shop"},
)

# Route to the cheapest provider
response = client.chat.completions.create(
    model="openai/gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
    extra_body={"provider": {"sort": "price"}},
)

# Full routing control
response = client.chat.completions.create(
    model="openai/gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
    extra_body={
        "provider": {
            "allow": ["alice-shop", "bob-relay"],
            "sort": "price",
            "allow_fallbacks": True,
            "max_price": {"prompt": 0.000003, "completion": 0.000015},
        }
    },
)

You can also use the typed helper:

from onlist import ProviderRouting

routing = ProviderRouting(
    allow=["alice-shop", "bob-relay"],
    sort="price",
)

response = client.chat.completions.create(
    model="openai/gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
    extra_body={"provider": routing.model_dump(exclude_none=True)},
)

Streaming

stream = client.chat.completions.create(
    model="anthropic/claude-sonnet-4",
    messages=[{"role": "user", "content": "Write a haiku about APIs"}],
    stream=True,
)

for chunk in stream:
    content = chunk.choices[0].delta.content
    if content:
        print(content, end="", flush=True)

Async Usage

import asyncio
from onlist import AsyncOnlist

async def main():
    client = AsyncOnlist(api_key="sk-...")

    response = await client.chat.completions.create(
        model="openai/gpt-4o",
        messages=[{"role": "user", "content": "Hello!"}],
    )
    print(response.choices[0].message.content)

asyncio.run(main())

Marketplace API

Query the Onlist marketplace for models and providers:

from onlist import Onlist

client = Onlist(api_key="sk-...")

# List available models with pricing
models = client.marketplace.models.list(limit=10)
for m in models.data:
    print(f"{m['id']} - input: {m.get('pricing', {}).get('prompt', 'N/A')}")

# Get detailed model info with all provider offers
detail = client.marketplace.models.get("anthropic/claude-sonnet-4")
print(f"{detail.id} - {len(detail.providers)} providers")

# Browse providers
providers = client.marketplace.providers.list()
for p in providers.data:
    print(f"{p.slug} - score: {p.score}")

# Get a specific provider's profile
provider = client.marketplace.providers.get("alice-shop")
print(f"{provider.display_name} - {provider.model_count} models")

Other APIs

Since Onlist is fully OpenAI-compatible, all standard endpoints work:

# Embeddings
embedding = client.embeddings.create(
    model="openai/text-embedding-3-small",
    input="Hello world",
)

# Image generation
image = client.images.generate(
    model="openai/gpt-image-2",
    prompt="A sunset over Tokyo",
)

# Text-to-speech
audio = client.audio.speech.create(
    model="openai/tts-1",
    voice="alloy",
    input="Welcome to Onlist.",
)

Error Handling

For OpenAI-compatible API calls (chat.completions, embeddings, etc.), the standard openai exceptions are raised:

import openai
from onlist import Onlist

client = Onlist(api_key="sk-...")

try:
    response = client.chat.completions.create(
        model="openai/gpt-4o",
        messages=[{"role": "user", "content": "Hello"}],
    )
except openai.AuthenticationError:
    print("Invalid API key")
except openai.RateLimitError as e:
    print(f"Rate limited: {e.message}")

For marketplace API calls (client.marketplace.*), Onlist-specific exceptions are raised:

from onlist import Onlist, AuthenticationError, APIError

client = Onlist(api_key="sk-...")

try:
    providers = client.marketplace.providers.list()
except AuthenticationError:
    print("Invalid API key for marketplace")
except APIError as e:
    print(f"API error {e.status_code}: {e.message}")

Migrate from OpenAI or OpenRouter

Already using the OpenAI SDK? Change one line:

- from openai import OpenAI
- client = OpenAI(api_key="sk-...")
+ from onlist import Onlist
+ client = Onlist(api_key="sk-...")

Or, if you prefer to keep using openai directly:

from openai import OpenAI

client = OpenAI(
    api_key="your-onlist-key",
    base_url="https://onlist.io/v1",
)

Routing Metadata

Onlist returns routing information in response headers. Access them to see which provider actually served your request:

# Use the with_raw_response pattern from the openai SDK:
raw_response = client.chat.completions.with_raw_response.create(
    model="openai/gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
)
print(raw_response.headers.get("x-onlist-route-id"))
print(raw_response.headers.get("x-onlist-provider"))

# Parse the completion as usual:
response = raw_response.parse()
print(response.choices[0].message.content)

Links

• Onlist Website
• API Documentation
• Model Catalog
• Provider Directory
• GitHub