Claude Opus 5.5
22 September 2026
Claude Opus 5.5 from Anthropic, language model published 2026-09-22. Notable for: discretionary.
Where it runs
| Provider | Model id | Context | Input | Output |
|---|---|---|---|---|
| OpenRouter | anthropic/claude-opus-5.5 | 1M | $4.00/M | $20/M |
Abstract
Claude Opus 5.5 is our first release since we called for pacing the frontier. It was tested before release by external evaluators, including Frontier Design and METR. On our automated behavioral audit, the most comprehensive alignment test we run, Opus 5.5 is the strongest-performing model we’ve tested to date. It also comes with the safeguards we’ve developed for our most capable models.
Sources: Epoch AI, OpenRouter. This entry was generated from a dataset and has not been edited by hand.