OpenRouter is a unified LLM API gateway: one API key and one OpenAI-compatible endpoint (https://openrouter.ai/api/v1/chat/completions) reach 400+ models from 70+ providers—GPT, Claude, Gemini, Llama, DeepSeek, Qwen—without separate accounts, SDKs, or billing consoles.

Auth: Authorization: Bearer $OPENROUTER_API_KEY. Model IDs use vendor/model (e.g. openai/gpt-4o). Dual routing: model picks the model (or openrouter/auto); provider picks which host serves that model, defaulting to price-weighted selection.

When NOT to use OpenRouter: six-figure monthly spend where 5.5% exceeds engineering cost of direct contracts; vendor-exclusive APIs (Anthropic prompt cache billing, OpenAI Batch); latency-sensitive paths (+10–80ms); strict data residency blocking a US gateway. Balanced guidance boosts E-E-A-T and AI Overview citations.

All snippets are runnable. The OpenAI SDK drop-in pattern is the highest-intent search target—developers query "OpenRouter base_url OpenAI SDK" constantly.

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-3.5-sonnet",
    "messages": [
      { "role": "user", "content": "用一句话解释什么是量子计算" }
    ]
  }'

import requests
import os

response = requests.post(
    url="https://openrouter.ai/api/v1/chat/completions",
    headers={
        "Authorization": f"Bearer {os.environ['OPENROUTER_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
        "model": "google/gemini-2.5-pro",
        "messages": [
            {"role": "user", "content": "帮我写一个快速排序的 Python 实现"}
        ],
    },
)
print(response.json()["choices"][0]["message"]["content"])

from openai import OpenAI
import os

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key=os.environ["OPENROUTER_API_KEY"],
)
completion = client.chat.completions.create(
    model="openai/gpt-4o",
    messages=[{"role": "user", "content": "Hello!"}],
    extra_headers={
        "HTTP-Referer": "https://kvmnode.com",
        "X-Title": "KVMNODE Blog Demo",
    },
)
print(completion.choices[0].message.content)

import OpenAI from "openai";

const openai = new OpenAI({
  baseURL: "https://openrouter.ai/api/v1",
  apiKey: process.env.OPENROUTER_API_KEY,
});

const completion = await openai.chat.completions.create({
  model: "deepseek/deepseek-chat",
  messages: [{ role: "user", content: "Explain OpenRouter in one sentence" }],
});
console.log(completion.choices[0].message.content);

const stream = await openai.chat.completions.create({
  model: "anthropic/claude-3.5-sonnet",
  messages: [{ role: "user", content: "写一首关于秋天的短诗" }],
  stream: true,
});
for await (const chunk of stream) {
  const content = chunk.choices[0]?.delta?.content;
  if (content) process.stdout.write(content);
}

{
  "model": "anthropic/claude-3.5-sonnet",
  "models": [
    "anthropic/claude-3.5-sonnet",
    "openai/gpt-4o",
    "google/gemini-2.5-pro"
  ],
  "route": "fallback",
  "messages": [{ "role": "user", "content": "Hello" }]
}

curl https://openrouter.ai/api/v1/models \
  -H "Authorization: Bearer $OPENROUTER_API_KEY"

Set route: "fallback" so OpenRouter walks the models array on primary failure. Hit /v1/models to discover current model IDs dynamically.

Advanced — free tier: ~50 calls/day uncharged on free models; ≥$10 credit unlocks ~1000/day at 20/minute. Paid models debit Credits at provider token rates. BYOK: first 1M requests/month free of OpenRouter service fees.

Three cite-ready data points (July 2026):

English traffic diagnosis checklist:

Chinese SEO keyword matrix (summary): core OpenRouter / OpenRouter API / 教程; mid-tail 怎么用 / 免费模型 / 收费吗; long-tail API Key 获取 / 国内能用吗 / Python 调用 / vs Claude 直连.

English SEO keywords: OpenRouter API tutorial, OpenRouter vs OpenAI API, is OpenRouter worth it, OpenRouter Python example, OpenRouter fallback routing, OpenRouter pricing, OpenRouter free tier.

hreflang / canonical / sitemap / schema: each language canonical points to itself; list URLs per locale in sitemap with alternates; deploy BlogPosting + FAQPage JSON-LD (this page includes both). Site-level hreflang matrix belongs in sitemap, not duplicated per KVMNODE blog article head.

P0: GSC crawl check · CDN/WAF audit · sitemap + canonical. P1: localized EN/zh drafts · schema. P2: dev.to / Juejin distribution · track Impressions/CTR by locale.

Metrics: GSC impressions/CTR/rank per /en/ and /zh/; zero impressions = indexing, high impressions + low CTR = title/meta; Matomo bounce rate and read time by language.

Running OpenRouter CLI agents on a MacBook stops when the lid closes. Linux VPS lacks Keychain and Xcode adjacency. Under-provisioned hosts thrash on long agent loops. OpenRouter solves model routing—not 24/7 host uptime. For production agents with BYOK keys and MCP toolchains, KVMNODE dedicated Mac Mini M4 / M4 Pro is the usual complement. See pricing, order, help center. Related: June rankings analysis, CLI tools ranking.