Claude Opus 5.5
Current version: 5.5 updated
Anthropic's flagship for long-running agentic coding and knowledge work
What's new in Claude Opus 5.5
- 1M token context window with up to 128K tokens per reply
- Adaptive thinking is always on, depth is set by the effort level
- Thinks more per turn than Opus 5 at the same effort level
- Sharper reading of dense charts, diagrams and screenshots
- Reliable knowledge cutoff of June 2026
What it's the best tool for
- 1,000,000-token context with up to 128,000 tokens per reply
- Adaptive thinking always on, with effort levels setting its depth
- Holds up across long agentic sessions with tool calling
- Reads values off dense charts, diagrams and screenshots precisely
- Accepts text, images and files including PDFs
- Reliable knowledge through June 2026
When to reach for something else
- Since the 4.7 generation Anthropic uses a newer tokenizer: per the vendor's docs the same text takes about 30 percent more tokens, so the bill for a familiar workload runs higher than an estimate based on older models
- Thinking cannot be disabled, every reply spends tokens on reasoning
- Noticeably slower at high and maximum effort levels
- No image, video or audio generation, text output only
- Broad safety classifiers: refusals on borderline topics and on requests to restate its internal reasoning
How Claude Opus 5.5 responds
Claude Opus 5.5
Four scenarios where it pays for itself
More about Claude Opus 5.5
Claude Opus 5.5 Online — Anthropic's New Flagship
Claude Opus 5.5 is Anthropic's top model, released on September 22, 2026 as the successor to Claude Opus 5. It is built for long-running agentic work: changes across a large codebase, multi-step tool chains, and heavy document analysis. The context window is 1 million tokens with up to 128K tokens in a single reply. On NetRoom it runs online, with no VPN, and you pay in rubles only for the tokens you actually use.
What is new versus Opus 5
The headline change is reasoning. On Opus 5 thinking could be switched off; on 5.5 adaptive thinking is always on, and the effort level sets its depth — from low for routine work up to the maximum for hard analysis. The default is medium effort, where Opus 5 defaulted to high. At the same effort level Opus 5.5 also tends to think longer per turn than Opus 5, so leave room in your output budget.
The second visible change is vision. The model reads values off dense charts, diagrams and screenshots far more precisely, so prompt-side workarounds built for earlier models are usually no longer needed. Its knowledge is reliable through June 2026; it accepts text, images and files including PDFs, and returns text only.
How tokens are counted here
One detail worth planning around. Starting with the 4.7 generation Anthropic switched to a newer tokenizer, and by the vendor's own documentation it produces roughly 30 percent more tokens for the same text than the previous one; the exact increase depends on the content and the shape of the workload. An estimate carried over from Sonnet 4.6 and earlier models will therefore come out low: the text is identical, the token count is not, and the bill for the same document lands higher than old habits suggest. Thinking tokens are spent on every turn as well, and they count too.
When to choose Opus 5.5
Reach for it when one shot is not enough: refactoring a large project, tracing a tangled bug through logs and diffs, reviewing a long PDF with complex layout, pulling numbers off dashboard screenshots, running multi-step tool pipelines. For short questions and quick drafts, Sonnet or Haiku are the better buy — Opus pays off where depth matters more than instant answers.
Why NetRoom
On NetRoom Claude Opus 5.5 runs right in the browser: no VPN, no foreign cards, pay-as-you-go in rubles for the tokens you use. Switch between Anthropic models in one interface — draft on a fast one, then hand the final pass to the flagship.
What changed Claude Opus 5.5
- + Added text model Claude Opus 5.5 (Anthropic).
Version history of Claude Opus 5.5
| Version | Date | What changed |
|---|---|---|
| 5.5 current |
|
Use Claude Opus 5.5 via the API
The same engine, straight from your code: one key and one balance for text, images, video and sound. Pay only for the requests you make.
curl https://netroom.ai/api/v1/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "anthropic/claude-opus-5.5", "messages": [{"role": "user", "content": "Hello"}]}'The format is OpenAI SDK compatible — point base_url at https://netroom.ai/api/v1 and use your NetRoom key.
The model id is already in the example. The full parameter reference and prices live in GET /api/v1/models and in the docs.
Try Claude Opus 5.5
right now
Free access to basic models. No card, no obligations.