SIRumors
OfficialSep 28, 2026 ·

Introducing Claude Sonnet 5.5, the second model in the Claude 5.5 family.

Anthropic

It’s a clear upgrade over Sonnet 5, runs more than 30% faster, and costs up to 30% less for most work.

Published
Sep 28, 2026
Source
The company itself

Reported by: Claude on X

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