Anthropic: Claude Opus 4.7 Fast Mode enters research preview — premium speed for the flagship model

Anthropic extended the Fast Mode research preview to Claude Opus 4.7 on May 12, 2026 — its latest flagship model for complex reasoning and agentic coding. Fast Mode was first introduced in February 2026 for Claude Opus 4.6, where it delivered up to 2.5× faster output token generation at a premium price.

How do developers activate Fast Mode on Opus 4.7?

Activation requires three parameters in a Messages API call: speed: "fast", model: "claude-opus-4-7", and the anthropic-beta: fast-mode-2026-02-01 header. Access is granted through the waitlist at claude.com/fast-mode. Anthropic notes that pricing, rate limits, and access policies remain identical to those of the Opus 4.6 Fast Mode variant.

What does Fast Mode concretely change in Opus 4.7?

Fast Mode optimizes the inference path for output speed while leaving Opus 4.7’s intellectual capabilities untouched. Opus 4.7 was released on April 16, 2026, at the same $5/$25 per million input/output token price as Opus 4.6, but carries capability improvements in reasoning, agentic coding, and a new tokenizer.

The premium tier in Fast Mode means clients pay extra for speed — a trade-off relevant for interactive chat applications, long-running agent workflows, and compile-on-demand scenarios where latency blocks the flow of work.

Fast Mode’s place in the Anthropic stack

Anthropic has accelerated its release pace in 2026: Opus 4.6 (February 5), Opus 4.7 (April 16), Claude Platform on AWS (May 11), and now the Fast Mode expansion (May 12). Fast Mode is currently available only for Opus 4.6 and 4.7 — Sonnet and Haiku lines have no equivalent feature, suggesting that premium speed is positioned exclusively for users who already rely on flagship intelligence but find latency becoming a bottleneck.