Latest Model Resolution

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Overview

• Product teams who want to always use the best-in-class model from a specific author without monitoring release notes.
• Internal tools and prototypes where you care about “latest Claude Opus” more than a specific version pinned for reproducibility.
• Rolling migrations where you want to defer version pinning until after a release has stabilised.

​

Usage

import { OpenRouter } from '@openrouter/sdk';

const openRouter = new OpenRouter({
  apiKey: '<OPENROUTER_API_KEY>',
});

const completion = await openRouter.chat.send({
  model: '~anthropic/claude-opus-latest',
  messages: [
    {
      role: 'user',
      content: 'Summarize this in one sentence: ...',
    },
  ],
});

console.log(completion.choices[0].message.content);
// The `model` field reflects the concrete version that served the request.
console.log('Resolved to:', completion.model);

const response = await fetch('https://openrouter.ai/api/v1/chat/completions', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer <OPENROUTER_API_KEY>',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: '~anthropic/claude-opus-latest',
    messages: [
      {
        role: 'user',
        content: 'Summarize this in one sentence: ...',
      },
    ],
  }),
});

const data = await response.json();
console.log('Resolved to:', data.model);

import requests
import json

response = requests.post(
  url="https://openrouter.ai/api/v1/chat/completions",
  headers={
    "Authorization": "Bearer <OPENROUTER_API_KEY>",
    "Content-Type": "application/json",
  },
  data=json.dumps({
    "model": "~anthropic/claude-opus-latest",
    "messages": [
      {
        "role": "user",
        "content": "Summarize this in one sentence: ..."
      }
    ]
  })
)

data = response.json()
print('Resolved to:', data['model'])

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "~anthropic/claude-opus-latest",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

​

Response

{
  "id": "gen-...",
  "model": "anthropic/claude-opus-4.8",
  "choices": [
    {
      "message": {
        "role": "assistant",
        "content": "..."
      }
    }
  ],
  "usage": {
    "prompt_tokens": 12,
    "completion_tokens": 85,
    "total_tokens": 97
  }
}

​

How It Works

1. Slug recognition: OpenRouter sees the ~ prefix and identifies which family the alias points to (for example ~anthropic/claude-opus-latest → the Claude Opus family).
2. Target selection: The newest visible model in that family is selected. When a new version ships, it takes over automatically, with no client changes required.
3. Request forwarding: Your request is forwarded to the resolved model and routed across providers exactly as if you’d called that concrete slug directly.
4. Transparent reporting: The response’s model field reports the concrete model that served the request (for example anthropic/claude-opus-4.8), so you can always tell which version answered any given call.

​

Pricing and Capabilities

• Clients that list models for their users see accurate per-token prices.
• Capability-gated flows (for example “only offer this model for vision requests”) see up-to-date modalities.
• Cost dashboards reflect the real rate charged, because requests are billed at the concrete model’s price.

​

Compatibility Contract

• reasoning: { effort: "none" } is upgraded to the lowest effort the model supports (for example minimal or low).
• reasoning: { enabled: false } is flipped to enabled, again at the lowest supported effort.
• reasoning: { max_tokens: 0 } is treated the same way, and the zero token budget is dropped.

​

Use Cases

• Always-on assistants: Point user-facing agents at ~anthropic/claude-sonnet-latest and get new releases for free.
• Evaluation harnesses: Benchmark “the latest” model per author without editing configs.
• Enterprise pilots: Share a slug with a partner and upgrade them in place when a newer model ships.

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Limitations

• Versions can change at any time: When a newer model is rolled in as the latest target, subsequent requests resolve to it. If your application requires a fixed version for reproducibility (for example in regression tests), use the concrete model slug instead.
• Only latest: The router always resolves to the newest eligible model. There is no built-in way to pin to “second newest” or to roll back through the alias — to downgrade, switch to a concrete slug.
• Aliases and hidden models are excluded: The router never resolves to another alias slug or to models that have been hidden.

​

Pinning to a Specific Version

{
  "model": "anthropic/claude-opus-4.8"
}

​

Related

• Auto Router - Cross-model intelligent selection (paid models)
• Free Models Router - Route to available free models
• Model Variants - :free, :nitro, :thinking, and other suffixes
• API Reference: Chat Completions