2
Claude Opus 5.5 fast mode exits research preview, becomes default-available
2026-10-15
Anthropic's API changelog for October 15, 2026 states that fast mode for Claude Opus 5.5 is out of research preview: requests no longer need the fast-mode beta header, and Opus 5.5 now has a default fast-mode rate limit across Start, Build, and Scale usage tiers. Fast mode for Claude Opus 5 and Opus 4.8 remains in research preview. Fast mode for Opus 5.5 is also now available on Claude in Microsoft Foundry for Azure deployments.
Significance 2: An incremental serving/availability change (removing a beta gate) for an existing model is a minor technology update, not a new capability or pricing change.
technology Release
Sources
- primary Claude Platform release notes retrieved 2026-10-16
Affected axes
Output speed