How to Use the OpenRouter API
to Call GPT, Claude & Gemini (2026 Guide)

OpenRouter is an aggregation layer, not a model vendor. Authentication uses Authorization: Bearer $OPENROUTER_API_KEY. The request format matches OpenAI Chat Completions, so existing OpenAI SDK code works after changing base_url and api_key. Models use the provider/model naming scheme—e.g. openai/gpt-4o, anthropic/claude-3.5-sonnet, google/gemini-2.5-pro.

• Account sprawl: Direct integrations require separate keys, SDKs, and billing portals for OpenAI, Anthropic, Google, Meta, and DeepSeek.
• No built-in failover: When one provider rate-limits or goes down, your app must implement retries and provider switching yourself.
• Fragmented cost tracking: Reconciling usage across five dashboards every month is error-prone.

OpenRouter makes two independent routing decisions on every request:

• Automatic failover: On rate limits or errors, OpenRouter switches to the next available provider or fallback model via the models array—your app typically never sees a 500.
• Free tier: 25+ free models; ~50 calls/day without credits; 1,000/day and 20/min after topping up ≥$10.
• Pricing model: No token markup—provider rates pass through. A 5.5% fee (min $0.80) applies only when buying credits. BYOK mode: first 1M requests/month free, then 5% on equivalent usage.

Verify current behavior against official docs before shipping to production.

https://openrouter.ai/docs

https://openrouter.ai/docs/faq

• One key, every model: Swap models by changing one string—no adapter layers per vendor.
• Built-in failover: Configure models: ["anthropic/claude-3.5-sonnet", "openai/gpt-4o", "google/gemini-2.5-pro"] and let the gateway handle circuit breaking.
• Unified dashboard: Token spend, latency (TTFT), and throughput in one place.
• No token markup: Unlike many aggregators, OpenRouter passes provider pricing through; the 5.5% fee hits only credit purchases.
• Clear sweet spot: Prototyping, multi-model A/B tests, sub-$10k/month workloads, and any agent framework that should run on every frontier model.

When you should NOT use OpenRouter: Single-model workloads at tens of thousands of dollars per month where the 5.5% credit fee exceeds the cost of direct integration; vendor-specific features (Anthropic Prompt Caching, OpenAI Batch/Assistants, Google Vertex tooling); latency-sensitive paths where an extra 10–80ms gateway hop matters; compliance requirements that forbid US third-party routing.

Including honest trade-offs builds E-E-A-T and matches how English developers actually search: "OpenRouter vs OpenAI API" and "is OpenRouter worth it" convert better than generic praise.

1. Create an account at openrouter.ai via GitHub or email.
2. Generate an API key under Settings → Keys. Store it as OPENROUTER_API_KEY—never commit it to git.
3. Top up credits (optional): Free models work without payment. Paid models require credits; ≥$10 unlocks higher free-tier quotas.
4. Pick a model from the Models page or GET /api/v1/models. Note the provider/model string.
5. Send your first request to https://openrouter.ai/api/v1/chat/completions and confirm choices[0].message.content returns.
6. Harden for production: Add HTTP-Referer and X-Title headers; configure a models fallback chain; run agent processes on an always-on macOS host so laptop sleep does not kill long-running jobs.

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": "Explain quantum computing in one sentence" }
    ]
  }'

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://calmvps.com",
        "X-Title": "CALMVPS 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);

Streaming responses:

const stream = await openai.chat.completions.create({
  model: "anthropic/claude-3.5-sonnet",
  messages: [{ role: "user", content: "Write a short poem about autumn" }],
  stream: true,
});
for await (const chunk of stream) {
  const content = chunk.choices[0]?.delta?.content;
  if (content) process.stdout.write(content);
}

Model fallback for high availability:

{
  "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"

• Endpoint: https://openrouter.ai/api/v1/chat/completions
• Catalog: 400+ models from 70+ providers
• Free models: 25+ available; ~50 calls/day without credits; 1,000/day after ≥$10 top-up
• Credit fee: 5.5% on purchases (minimum $0.80); +5% for crypto payments
• BYOK: Bring your own provider keys—first 1M requests/month free, then 5% on equivalent usage
• Gateway latency: Roughly 10–80ms added vs direct provider calls

Per-model token rates live on the OpenRouter Models page and change when providers update pricing.

https://openrouter.ai/models

• Is OpenRouter free? 25+ models are free with rate limits. Paid models bill at provider rates; you pay a 5.5% fee only when buying credits.
• Does OpenRouter charge a fee on tokens? No markup on token pricing—only on credit purchases.
• Is OpenRouter worth it? Yes for multi-model apps and failover needs; no for single-vendor high-volume or compliance-sensitive workloads.
• What models does OpenRouter support? 400+ models—query /api/v1/models for the live list.
• Is OpenRouter safe? Traffic passes through a US gateway. Use BYOK or direct APIs for sensitive data.
• OpenRouter vs OpenAI API? OpenRouter is a gateway that can call OpenAI models plus Anthropic, Google, DeepSeek, and others.
• How does OpenRouter pricing work? Pay-as-you-go token billing at provider rates plus credit-purchase fees; no fixed monthly subscription.
• OpenRouter Python example? Point the OpenAI SDK at https://openrouter.ai/api/v1 or use raw HTTP POST with requests.

If you publish this tutorial on a bilingual blog and English impressions stay at zero, work through these layers in order:

P0 — Crawl and index (highest ROI):

• CDN/WAF blocking Googlebot: Test with Google Search Console URL Inspection, not just your browser.
• Missing hreflang: Google may treat English as duplicate of Chinese.
• robots.txt / noindex mistakes: Ensure /en/ is not disallowed.
• Sitemap gaps: List each language separately with alternate annotations.
• CSR empty shells: SPAs without SSR/SSG return blank HTML to crawlers.

P1 — Content (do not translate—rewrite):

• English users search "OpenRouter vs OpenAI API" and "is OpenRouter worth it," not literal translations of Chinese headlines.
• Cover query fan-out: what it is, how to use it, pricing, comparisons, safety, and limitations in one article.
• Add verifiable specifics—real bills, tested latency, version numbers—for E-E-A-T.

English keyword targets: OpenRouter API, OpenRouter tutorial, OpenRouter vs OpenAI API, OpenRouter Python example, OpenRouter OpenAI SDK drop-in replacement, OpenRouter fallback routing, is OpenRouter free.

Technical SEO: Subdirectory URLs (/en/, /zh/), self-referencing canonicals, BlogPosting + FAQPage JSON-LD, separate GSC property filters per language prefix.

Distribution: dev.to, Reddit (r/LocalLLaMA, r/programming), Hacker News, Indie Hackers—not just Chinese platforms where your domain already has links.

• P0 this week: GSC index check for /en/; audit CDN/WAF logs; fix hreflang, canonical, sitemap entries.
• P1 writing: Independent English and Chinese drafts; embed keywords in title, intro, H2, FAQ; add structured data.
• P2 distribution: dev.to + community posts; submit sitemaps to GSC and Baidu Webmaster Tools for Chinese URLs.

Track separately by language prefix: GSC impressions and CTR for /en/ vs /zh/—zero impressions means indexing, not ranking, is broken. Monitor bounce rate and read time in Umami, Plausible, or GA4. Spot-check 3–5 core keywords monthly in an incognito US Google session.

OpenRouter solves model routing, but your agent runtime still needs a reliable host. Laptop sleep, Linux VPS without Xcode/Metal, and shared VM contention are common failure modes for Cursor, OpenClaw, and custom agents calling OpenRouter.

For production iOS CI/CD and always-on AI agent automation, CALMVPS bare-metal Mac Mini rental is the stronger foundation: dedicated Apple Silicon, root access, 7×24 uptime, and 120-second provisioning—decouple your gateway from your inference backend and swap models without touching runtime stability.