Claude Opus 4.8 · impossibl

Claude Opus 4.8 is an Opus-tier model from Anthropic aimed at agentic coding, legal and financial document work, and complex multi-step reasoning in enterprise workflows. Over Opus 4.7 it is far more willing to flag flaws and uncertainties, catches its own mistakes during agentic runs, and uses tokens more efficiently.

Base model All models on this base All models of the provider to the provider

Input, $/1M $5.00

Output, $/1M $25.00

Cache read $0.50

Cache write $6.25

Context 1 000 000

Accepts images, text

Last checked 04.11.2026 12:00:14 UTC

Source provider's page

Price alerts

API

OpenAI-compatible API: the official OpenAI SDKs work with this base URL. Replace YOUR_API_KEY with your key from the provider.

API base URL	`https://api.impossibl.com/v1`
Endpoint	`https://api.impossibl.com/v1/chat/completions`
Model id	`anthropic/claude-opus-4-8`

curl

curl https://api.impossibl.com/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "anthropic/claude-opus-4-8", "messages": [{"role": "user", "content": "Hello!"}], "max_tokens": 256}'

Python

import requests

r = requests.post(
    "https://api.impossibl.com/v1/chat/completions",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
      "model": "anthropic/claude-opus-4-8",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ],
      "max_tokens": 256
    },
)
print(r.json())

JavaScript

const r = await fetch("https://api.impossibl.com/v1/chat/completions", {
  method: "POST",
  headers: {Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json"},
  body: JSON.stringify({
    "model": "anthropic/claude-opus-4-8",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ],
    "max_tokens": 256
  }),
});
console.log(await r.json());

Request (JSON)

{
  "model": "anthropic/claude-opus-4-8",
  "messages": [
    {
      "role": "user",
      "content": "Hello!"
    }
  ],
  "max_tokens": 256
}

Response (JSON)

{
  "id": "chatcmpl-...",
  "object": "chat.completion",
  "model": "anthropic/claude-opus-4-8",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hi! How can I help?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}

The address is taken from the provider's model list; check it against the provider's documentation.

Provider's API documentation

Source: AI Rate Card, https://airatecard.com/en/c/offer%3Aimpossibl%7Canthropic/claude-opus-4-8, prices checked 2026-11-04; seller's page: https://impossibl.com/models/anthropic/claude-opus-4-8

Technical details

ID: offer:impossibl|anthropic/claude-opus-4-8