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Reasoning · Anthropic

Claude Opus 5 in the EU, processed in European data centres

Claude Opus 5 is Anthropic's large frontier model, released in July 2026, with a one-million-token context window and adaptive thinking. On inference.eu you call it with the Anthropic Messages or OpenAI request format, your requests are processed in EU data centres, and nothing you send is used for training.

Contact salesExample request
  1. 01Context window: 1,000,000 tokens
  2. 02EU data centres
  3. 03Proprietary

What Claude Opus 5 is

Claude Opus 5 is a closed frontier model from Anthropic, released on 24 July 2026 as the successor to Claude Opus 4.8. It reads text and images and writes text. Its context window is one million tokens, and a single response can be up to 128K tokens long. Anthropic gives its reliable knowledge cutoff as May 2026.

Opus 5 uses adaptive thinking: the model decides how much to reason before it answers, and an effort setting steers how deep it goes. Anthropic's default effort for Opus 5 is high. Anthropic does not publish the parameter count or the weights, so the model is only available as a service.

What it does well, and where it falls short

Anthropic reports the largest gains over Opus 4.8 in agentic coding, computer use and long-horizon knowledge work. Opus 5 is much better at checking its own work and iterating until a task succeeds, which matters most in long agent runs where one wrong step can derail the rest.

It is a large model, so it is slower and costs more per token than Claude Sonnet 5.5 or Claude Haiku 5.5. For short, well-defined tasks such as classification or simple extraction, a smaller model is usually the better choice. Anthropic has since released Claude Opus 5.5 and lists Opus 5 as a legacy model that remains available.

Calling Claude Opus 5 through the API

inference.eu speaks the Anthropic Messages format, so the official Anthropic SDKs work once you change the base URL and the key. Claude Code works the same way: set ANTHROPIC_BASE_URL to the inference.eu host, ANTHROPIC_AUTH_TOKEN to your inference.eu key, and choose claude-opus-5 as the model.

If your code uses the OpenAI SDKs, LangChain, LlamaIndex or the Vercel AI SDK, you can call the same model through the OpenAI-compatible endpoint with the model set to claude-opus-5. Streaming, tool calls and image input work in both formats, so you can keep the client you already have.

Claude Opus 5 with data processed in the EU

When you call Claude Opus 5 on inference.eu, your prompts, images and the model's responses are processed in data centres in the European Union. They are used to answer your request and are never used to train any model.

We sign one data processing agreement under Article 28 of the GDPR with every customer and provide our list of subprocessors, so your data protection officer can see who handles the data and where. That one agreement covers Claude Opus 5 and every other model on inference.eu. Billing is in euros.

claude-opus-5 · Python
import os
from openai import OpenAI

client = OpenAI(base_url="https://api.inference.eu/v1", api_key=os.environ["INFERENCE_EU_API_KEY"])

response = client.chat.completions.create(
    model="claude-opus-5",
    messages=[{"role": "user", "content": "Summarise this contract in five bullet points."}],
)
print(response.choices[0].message.content)

What teams use it for

  • 1

    Long-running coding agents

    Run Claude Code or your own agent on large repositories, with Opus 5 planning changes, running tools and checking its own results over many steps.

  • 2

    Complex knowledge work

    Draft and review long reports, contracts and analyses where the model has to keep many documents and constraints in view at once.

  • 3

    Computer use and screen tasks

    Let an agent read screenshots of web apps and internal tools and decide what to do next, with requests processed in the EU.

Claude Opus 5: common questions

The questions buyers, developers and legal teams ask us most. Something missing? Ask us directly.

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