nRouter Python SDK

The official Python client library for the nRouter LLM gateway.

One API key for models across six provider clouds — OpenAI, Anthropic, AWS Bedrock, Google Vertex AI, Azure Foundry, and Alibaba Cloud. Features built-in automatic cost tracking (x-nr-* metadata capture), guardrails, response caching, prompt templates, and typed exception handling.

Installation

pip install nrouter-sdk

Authentication & Environment Variables

The SDK automatically resolves its configuration from environment variables.

1. Set your environment variables

# Required: Get your API key from https://nrouter.ai/dashboard/keys
export NROUTER_API_KEY="sk-nrouter-your-api-key-here"

# Optional: Override base URL (e.g. for staging or local proxy)
export NROUTER_BASE_URL="https://api.nrouter.ai/v1"

2. Configuration Matrix

You can also pass parameters explicitly in code:

from nroutersdk import nRouter

client = nRouter(
    api_key="sk-nrouter-your-api-key-here",
    base_url="https://api.nrouter.ai/v1",
)

Quick Start

Synchronous Client (nRouter)

from nroutersdk import nRouter

# Uses context manager to ensure clean connection pool shutdown
with nRouter() as client:
    response = client.chat.completions.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[
            {"role": "system", "content": "You are a helpful assistant."},
            {"role": "user", "content": "Hello from Python!"},
        ],
    )

    # Output completion text
    print(response.choices[0].message.content)

    # Cost and Request Metadata (captured automatically from x-nr-* headers)
    meta = client.last_response
    print(f"Request ID: {meta.request_id}")
    print(f"Model:      {meta.model}")
    if meta.cost is not None:
        print(f"Cost:       ${meta.cost:.6f}")
    else:
        print(f"Cost:       unpriced ({meta.cost_status})")

Asynchronous Client (AsyncnRouter)

import asyncio
from nroutersdk import AsyncnRouter

async def main():
    async with AsyncnRouter() as client:
        response = await client.chat.completions.create(
            model="anthropic/claude-sonnet-4-5-20250929",
            messages=[{"role": "user", "content": "Explain quantum computing in one sentence."}],
        )

        print(response.choices[0].message.content)
        print(f"Cost: ${client.last_response.cost}")

asyncio.run(main())

Core Capabilities & Examples

📓 Interactive Jupyter Notebook

Try the SDK interactively with notebooks/quickstart.ipynb.

1. Streaming Responses

from nroutersdk import nRouter

with nRouter() as client:
    stream = client.chat.completions.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[{"role": "user", "content": "Write a short poem about routers."}],
        stream=True,
    )

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

2. Anthropic Messages API

Use Anthropic's Messages format directly on the exact same sk-nrouter- API key:

from nroutersdk import nRouter

with nRouter() as client:
    # Pre-call token counting (Free route)
    count = client.messages.count_tokens(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[{"role": "user", "content": "Hello!"}],
    )
    print(f"Token count: {count['input_tokens']}")

    # Create message
    message = client.messages.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[{"role": "user", "content": "Hello via Anthropic Messages!"}],
        max_tokens=256,
    )
    print(message["content"][0]["text"])

3. Function & Tool Calling

Define function schemas and let the model decide when to invoke external tools:

import json
from nroutersdk import nRouter

tools = [
    {
        "type": "function",
        "function": {
            "name": "get_stock_price",
            "description": "Get the current stock price for a symbol",
            "parameters": {
                "type": "object",
                "properties": {
                    "symbol": {"type": "string", "description": "Stock ticker symbol, e.g. AAPL"},
                },
                "required": ["symbol"],
            },
        },
    }
]

with nRouter() as client:
    response = client.chat.completions.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[{"role": "user", "content": "What is the stock price of AAPL?"}],
        tools=tools,
        tool_choice="auto",
    )

    msg = response.choices[0].message
    if msg.tool_calls:
        for tool_call in msg.tool_calls:
            print(f"Tool called: {tool_call.function.name} with args: {tool_call.function.arguments}")

4. Structured JSON Outputs

Enforce typed JSON object generation using response_format:

import json
from nroutersdk import nRouter

with nRouter() as client:
    response = client.chat.completions.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[
            {"role": "system", "content": "Extract data into JSON with keys: name, title, company."},
            {"role": "user", "content": "Sarah Connor is the Lead Security Engineer at Cyberdyne."}
        ],
        response_format={"type": "json_object"},
    )

    data = json.loads(response.choices[0].message.content)
    print(data)  # {'name': 'Sarah Connor', 'title': 'Lead Security Engineer', 'company': 'Cyberdyne'}

5. Response Metadata & Cost Tracking

The gateway emits canonical x-nr-* headers with every response. client.last_response captures these automatically:

meta = client.last_response

print("Request ID:        ", meta.request_id)
print("Exact Cost (USD):  ", meta.cost)
print("Cost Status:       ", meta.cost_status)        # "exact" or "unpriced"
print("Served Model:      ", meta.model)
print("Input Tokens:      ", meta.input_tokens)
print("Output Tokens:     ", meta.output_tokens)
print("Total Tokens:      ", meta.total_tokens)
print("Cache Read Tokens: ", meta.cache_read_tokens)
print("Cache Write Tokens:", meta.cache_write_tokens)
print("Gateway Cache:     ", meta.response_cache)     # "hit", "miss", or None
print("Cache Age (s):     ", meta.response_cache_age) # seconds on hits
print("Limit Source:      ", meta.limit_source)       # "key", "team", "org", or None

Note on Cost Accuracy: Unpriced models return cost=None and cost_status="unpriced". Never treat None as $0.00 — free routes (like /v1/messages/count_tokens) emit no cost header, while billable inferences always track usage.

Error Handling

All gateway refusals are converted into typed exceptions:

from nroutersdk import (
    nRouter,
    nRouterGuardrailBlockedError,
    nRouterCreditError,
    nRouterRateLimitError,
    nRouterAuthenticationError,
    nRouterNotFoundError,
    nRouterRequestError,
    nRouterServiceError,
    nRouterError,
)

with nRouter() as client:
    try:
        response = client.chat.completions.create(
            model="claude-sonnet-4-5-20250929",
            messages=[{"role": "user", "content": "Analyze confidential data..."}],
        )
    except nRouterGuardrailBlockedError as e:
        print(f"Blocked by guardrail: {e}")
    except nRouterCreditError as e:
        print(f"Insufficient credits: {e}")
    except nRouterRateLimitError as e:
        print(f"Rate limit exceeded: {e}")
    except nRouterAuthenticationError as e:
        print(f"Invalid API key: {e}")
    except nRouterNotFoundError as e:
        print(f"Model not found: {e}")
    except nRouterServiceError as e:
        print(f"Gateway service unavailable: {e}")
    except nRouterError as e:
        print(f"General nRouter error: {e}")

Enterprise Configuration & Proxies

Custom Proxy, SSL Certificates & Timeouts

Pass custom httpx2.Client or timeout configurations for corporate networks:

import httpx2 as httpx
from nroutersdk import nRouter

# Configure proxy, custom SSL context, and timeouts
http_client = httpx.Client(
    proxy="http://proxy.corporate.internal:8080",
    verify="/path/to/corporate-ca.crt",
    timeout=httpx.Timeout(60.0, connect=10.0),
)

with nRouter(http_client=http_client, max_retries=3) as client:
    response = client.chat.completions.create(
        model="anthropic/claude-sonnet-4-5-20250929",
        messages=[{"role": "user", "content": "Hello behind enterprise proxy!"}],
    )

Supported Endpoints

All endpoints route through https://api.nrouter.ai/v1:

Documentation & Resources

• nRouter Documentation
• API Reference
• Python Quickstart Guide
• Live Model Catalog
• Dashboard & API Keys