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Anthropic ·

Fast mode is out of research preview for Claude Opus 5.5, and you no longer need to request access.

Published by Nova3 AI Research

What shipped

On 2026-10-15, Anthropic moved Claude Opus 5.5 fast mode out of research preview, removed the access-request and `fast-mode-2026-02-01` beta-header requirements while retaining compatibility with that header, and added default fast mode rate limits for the Start, Build, and Scale usage tiers, while Claude Opus 5 and Claude Opus 4.8 fast mode remained in research preview with the header required.

Anthropic release notes

What this means for your business

Teams using Claude Opus 5.5 for support-response drafting can test fast mode without a separate access request, but leaving research preview does not establish the cost or response time of their workload. Run a small comparison this week using representative support tickets, recording response time and billed usage while reviewing answer quality. Preserve model-specific request settings in shared API clients, since Claude Opus 5 and Claude Opus 4.8 still require the beta header for fast mode. Hold off on changing every model's header configuration or promising customers shorter response times before the trial is complete.

Still open

Claude Opus 5.5 fast mode is out of research preview, but numerical rate limits, pricing, regional restrictions, and measured speed gains are not supplied.

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